Like you I can't see any point in spending more than you have to. I bought a Garmin GPS12XL having seen another group member using one. My reasons were:
I liked the shape and small compact size + good battery life.
The display was much clearer than the cheap Magellan ones then available.
I could (just) afford it.
I bought the XL version because at that time it had a lower battery drain than the non XL version; 24h c.f. 12h. The XL version also has a city database which frankly I have found absolutely useless for aviation (and possibly useless for anything else as well). The standard GPS12 now has the same 24h battery life as the GPS12XL.
I recommend just doing what I did, enter all your own waypoints. I just add them before a trip as I need them. I tend to put in VORs NDBs and airfields I need. Gradually the database builds up to something very useful.
You can get a cable to interface with a PC and enter the waypoints more efficiently, but I haven't bothered because I only enter a few each trip.
Answers to your questions:
1. No
2. No
3. GPS12