Re: What do you wish you had known before buying your first boat?
Your boat needs to meet three different needs;
1) sailing - obviously. It needs to sail. It would be nice for it to sail well. You need to be able to handle the boat, so the gear must be placed so that the crew (two of you?) can reach everything and not get in each others way.
2) camping - as you describe weekending on it. The port-a-potty needs some amount of privacy, you need to be able to store and prepare food (and beer - lots of beer if you're gonna be sailors!). Room for all your stuff for a few days.
3) sleeping and living on deck and below - can you lay flat out in the cockpit? Is there room enough in the bunk for both of you? If the main traveler cuts across the middle of the cockpit is there room to sit and lounge (the cockpit will be a place where you spent a lot of time). Obviously #1 and #3 can conflict.
The biggest thing I can recommend is that you lay down in the bunk (I know, it looks silly but you need to know if it fits you both), lay down in the cockpit. On a warm night you may want to sleep in the cockpit. Sit in the cockpit as if to eat a meal. Both of you stand and sit below in the salon. If its raining you may both be there reading till the sun comes back out.
Folks here can give you lots of advise on which boats sail well and are well made in your price range. You need to know which one "fits" the two of you.
And then you will buy one. And then you will learn what you didn't know and what we didn't think to tell you... sorry for that in advance!