I work from the boat a couple of days a week. I'm in the process of switching marinas right now and had to evaluate marinas around DC last year as part of looking at a contract. Here's what I've learned (sometimes the hard way).
WiFi - don't assume the marina will have it. If they do don't assume you'll be able to access it. What a lot of marinas around here call "free WiFi" is a cheapie wireless router in the club house -- and a weak or non-existant signal on your boat. In my current marina I built a wireless repeater using DD-WRT and a cheap wireless router. It takes a signal too weak for my laptop to even see and boosts it to five bars with no external antenna to reg/de-rig when you sail. Good solution, but only if you're a bit of a geek.
A simpler solution, and what I'll be using in my new marina, which has no WiFi, is the Nokia E71x. It's Nokia's version of the Black Berry with one important exception - it has a wireless router built in. With a Black Berry I'd have to buy a $65/month tethering option, with the Nokia I only have to buy a $15/month data option + a one time $89 fee for a phone upgrade.
Other options are FIOS or a Cable modem. Just about every marina has a cable hookup for their slips. They may not let Verizon run FIOS out on their dock, especially if they no longer have phone hookups at the slips, and many don't. With cell phones why bother?
You've already discovered eFax so you're covered there.
As for boat size. If you're 6'2 a Catalina 30 would be preferable to a 27. Nothing is worse than always hitting your head, not to mention bunk and v-berth sizes.
Now everyone's different, but I would find it hard to be a liveaboard on my Catalina 30. In a boat you're VERY limited for storage space, and you'll need a workable galley, room to stretch out and watch TV, have friends over etc. If you want to sail everything that isn't strapped down needs to be stowed in a locker. Weigh that against the fact that everything about boats is priced by the foot. Bigger = more expensive.
An alternative might be a storage bin on shore for things you don't use every day.
Now I know you said you're from Chicago, but I stop spending weekends on my boat when the temperature drops below 50 degrees at night. Boats have no insulation. You can see daylight between hatchboards. One, even two electric space heaters will only keep a boat so warm when it's sitting in 40 degree water and the air temp is in the 20's. And remember, when you crawl out from under that comforter you still have to walk down that cold, windy dock to the showers.
If you're going to do this I'd think southern climates, but as someone else mentioned you'll have to deal with humidity.
Also check with the marina as to their policies on live aboards. Many marinas forbid it.
Get any boat surveyed before you buy, and be careful of auctions. That bargain boat may not be a bargain after you add up what you needed to make it liveable. To see what I mean check out "Chip Ahoy" - The cost for my own hole in the ocean
. This is one man's cost to fully restore a Catalina 22. I bought a later model of the same boat that was complete and needed little work for $7,000. Fixer-uppers are not always bargains, even if you're doing the work yourself.
All that said, good luck and welcome! Just curious, what kind of work do you do?