Well, you are in for an education! (long)
Oookay. I can field this one. First, there's a good Yahoo Group dedicated to the boat. That is to say, there's a good bunch of people on Yahoo's crappy message boards, and they are dedicated to the boat up to and including excusing most of its faults, which are many, but which are broadly balanced by it's virtues. Follow that?
Bucc18 : Buccaneer 18 Discussion
First, the virtues. The boat is quick -- as fast as or faster than the Lightning, 470, Or Highlander. In its class (vintage big dinghies) only the 5o5, Thistle, and Flying Dutchman can beat it around the buoys, and it'll match the Thistle in stronger winds. In light air, the Bucc moves really well: it has a tall mast and a powerhead main. It will plane up to a close reach in 12-15 knots true. On reaches and runs, it'll plane on even less; like the FD, it carries its beam all the way aft, and it can MOVE if you hold it flat. Spinny is modest but main is large (114 sqft), so it has plenty of power downwind.
The boat is easy to set up -- 15 minutes to launch. One person can step the mast. It floats in 8 inches of water and at 500 lbs, it can be thrown around by one person. It will take a very small outboard or troller, but the thing paddles like a bloody canoe, so I can't imagine bothering with a motor. (Plus, with its low freeboard, you WILL drag any motor left on the bracket -- trust me on this.) The Bucc is cheap to buy, cheap to own, and very simple to fix. The class is large, growing, and extremely active: people lug their Buccs 3000 miles to race in Nationals or NOODs. They are a friendly group, willing to help with tips, parts, repairs, and crewing. You will not find a better gang to help you learn the boat and, if you want, to start racing with. Nickels is making new Buccs, so parts are available. Restrictive class rules hold annual costs down.
Within its window, the Bucc18 is simply a riot to sail. It accelerates out of the hole like a dragster, it turns fairly quick for 17' of waterline, and when it has the bit between its teeth, it's like clinging to the back of a thoroughbred. Mucho fun for not much money, and a hell of a training platform. I love sailing it ... when it's behaving itself.
Now the faults. The older boats could be hit or miss on quality, and they were not always well-appointed. Some have been updated with magic box jib tensioners and mast tabernacles; others have not. Some have had chainplates reinforced, some have really noodly spars, some will have soggy floatation foam. The older boats are a real mixed bag.
The hull form has the softest bilge you ever will see -- perfectly round chines -- so it will go from flat to 30 degrees heel (and back down) in an eyeblink; for all its claims to be a 'sit in rather than a sit-on boat,' you will need to hike
and hike hard to keep the boat upright and moving. It's tenderness makes it hard to get comfortable and impossible to find a groove in puffy conditions. You will be up and down every 10 seconds. New sailors may have trouble depowering the boat fast enuf to prevent capsize, and sailing at up to 45 degrees of heel can be disconcerting until you get used to it. The boat does firm up there, but by that point the weather helm has become ridiculous. The original marketing claimed the boat will hold six people;:laugher Nickles has sensibly reduced that number to four, but even then you need very calm winds. You cannot have anyone on the low side in a breeze, and the cockpit (while large) is cluttered with vang, centerboard trunk, mainsheet, and tiller; with a low boom, it takes precise choreography to get even three people across when tacking.
The boats vices become insuperable as the wind edges over 15 knots; you will need at least 375 lbs of crew weight to hold down the boat and keep it footing. Singlehanding becomes very difficult above 12 kts. The mainsail is twice the area of the jib and quite roachy; combined with the boat's radical heeling, it will round up very easily in a gust, and you will find yourself fighting the helm. Kicking up the CB halfway helps, but then the chineless boat develops shocking leeway. Class rules forbid reefing; I do it anyway, because I like to live. You can roller furl the jib to reduce sail, but then the boat has even more weather helm. It actually sails really well on jib only, but that's not so practical. Maybe a topping lift would help.
The boat could really benefit from a traveler, but it's not allowed. So the boom is prone to lifting on downwind headings. You will need to use the vang to prevent accidental jibes, esp. since the swept-back shrouds keep the boom from paying all the way out. Lack of traveler & backstay also means you have to depower the main by cracking the sheet, which again lifts the boom and makes the main breifly deeper. Can be quite alarming. Many people sail Buccs with a soft mainsail luff in higher winds, but it is kind of a half-assed way to control the boat. Reefing is better.
When you capsize -- you WILL capsize -- the boat is fairly easy to stand back up, even from a full turtle. Blow the sheets, maybe even loosen the main halyard. Standing on the CB will get it up real fast, but some CBs and hinge pins are pretty creaky -- be ready if it snaps off! I can right ours by myself, and I weigh 140 lbs. It will be harder in chop, however. The secret is patience: lean back and wait... wait ... wait... while the sails shed their water. Then it will come up all at once. Some people add pool noodles below decks and in the mast; not sure it's that big a deal.
I dumped our Bucc last Saturday, singlehanding in really puffy winds that eventually topped out at 30knots. Stuck the mast in the lake bottom, too.

I got it back up in five minutes, bailed it out enough to get moving -- the cockpit bailers need 5 kts boat speed to work -- and kept it together the rest of the day. In the boat's defense, it was the first time it tossed me in two years, despite some of the gnarliest, weirdest winds in America. But it took a lot of work to keep it that way & I've been playing this game since 1975.
The Buccaneer 18 is not the ideal boat for a beginner, for a singlehander, or for people for whom hiking or agility is problematic. But hey. If you can sail it, you can sail darn near anything.

I'd strongly advise finding someone with small boat experience who can show you the tricks. You should practice dumping and recovering it with someone who knows how. Even with your Sunfish experience, you might spend a few hours on jib only until you get the feel for her. Pointing and tacking will suffer, tho not as much as you'd think. And PFDs mandatory for everyone, all the time. I will not go out on that boat without one.
Finally, a few gear issues. The original Chrysler rudderhead was a cast aluminum truss & prone to breaking; the stainless pintle retaining clip didn't work; both led to lost rudder assemblies. So probably yours is an aftermarket: flat drilled aluminum plates. Use a clevis pin or RingDing to keep it attached if you capsize. The original chainplates often needed beefing up. The boom may have a permanent downward bend. The jibhead swivel is a constant irritation, tending to 'birdcage' the wire halyard. I want to replace the halyard with Spectra cord. The CB box is prone to weakness, cracking, and rotting; I am completely rebuilding ours as I type this.

There's a soft area in the hull just in front of the CB box; a trailer roller may punch right thru there. Decks & seats are not cored, but older boats can make scary crunching noises when you walk on them. The round bailers tend to leak; a little Vaseline can help, but many people replace them with new rectangular ones, which is not a trivial job. The round ones really get the water out fast, tho. Never yet sailed the Bucc without taking water over the rail.
Best of luck, enjoy your boat, and please post here or PM me if you have more questions. It's a fun boat if you can get past its fiery temper. More zing for the dollar you will not find in the boating world. Cheers!