I just joined the Contax G family myself. I, like you did a ton of research and was helped by many of the posters here, these folks are great!
I went the G2 route because I love black, I have always wanted a black RF with interchangeable lenses and had to splurge on the G2 (I believe they only made the G2 in black):
I also liked that the G2 has faster shutter speeds, the G1 is max 1/2000 and G2 can get 1/6000 when in Auto mode and 1/4000 in manual. I sometimes keep a roll of 400 at 800 and shoot indoor, but if I happen to be outdoor in sun, it can still handle it with a 1/6000 and wide open (f2.8). Third, I wanted the G2 because it was newer and for a battery dependent modern camera, I read a few postings of sellers talking about LCD bleed in their Gís. I figured the G2 being from >1996 and <2006 would have this occur less than the G1 which is <=1996.
Re flashes, I donít use them much and ended up just using my larger one, but there is some great info re Contax Gís and flashes here:

I donít think you can go wrong with any of the G lenses (well the 16mm is a bit of unique lens that is quite expensive). The focal length is a personal preference, so the 28mm is what I got, due to the subject matter I wanted to use it with. However, I believe in all my research, I read that the 90mm is not the best with the G1 due to the G1 not having a two tiered focusing methodology. As anyone will say, get good glass and upgrade later as you can afford, especially since these lenses are being bought up a lot for non-analog cameras as of late; however as Rich says, there are different breeds of G1ís if you take that route since they are so inexpensive, there are two: one that can take only some lenses and then the expanded one (green sticker). I am not sure off the top of my head which lenses the one without the green sticker will take, but think Rockewellís site breaks it down nice.

Note, any of my conclusions I made in my research could be wrong, make your own determination. Be careful buying a used expensive camera/lens, make sure you can evaluate it and return if it is not as described.

Last, I found this guy a great G owner, he really broke down the nuances:
Another resource for G2:

I have never used the T camera's, but I have always wanted one of those Fuji Klausse W cameras, which Fuji just decided to cease production of (more food for thought)....