What kind of server issues are there at this time? Please elaborate.
tonight everything was fine, but day before yesterday especially and the day before there were several instances where lobbies were not up and/or took a LONG time to refresh, I think it was because with Japan on everybody was online or something (which makes me worry about when the PS+ version is out).
In terms of AI YMMV, from my perspective the only time they ram is if you brake in the racing line way early or stuff like that (try that online, it will be the same), let's just say the AI is reasonably aggressive and not the typical pushover (like in GT6) that as soon as you end up even slightly in front they bow to your superior skills and let you pass. Personally on circuits the AI is not much of a challenge even on legend (especially if it's wet), on point to point it seems tougher, especially in the career races, but I have never felt the AI to be gratuitously dirty (nowhere near like online where sometimes you are side-by-side with somebody else and they'll plaster you into the wall)
You can brake late and make the corner sometimes, but try challenging other people's fast times and you'll see that if you don't drive well (meaning, correct line, apex, correct braking point(s)) there's no way you'll be competitive, I have been racing games for many years (my favorite is grand prix legends, to give you an idea, where I did fairly well, was in a league and all that) and I have felt at home with DC pretty much right away, it's no sim but it is quite enjoyable and mastering it is nowhere near easy (again, try to beat some of the fast time trial times on tracks and you'll see)
This said this last patch IMHO relaxed the penalties for hitting walls and others a bit too much, it should be like GT where if you hit anything or go off the track your lap is invalidated, I fear that the way things are now on some tracks it'd be faster to not brake and just hit the wall and bounce unfortunately, hopefully EVO will retighten things a bit.
It will be nice once private lobbies and further online improvements come in though, as nowadays it is very difficult to find a room with close competition, most of the time there are only a couple people joining and most of those drop leaving 1-2 to actually race, this at least is in circuit races, point-to-points seem to have more people but they are not my favorite so I don't tend to join those as often.