it is a 4th generation... 3rd gen was 86-89.

I had a 90 accord EX... got it with 190kmi on it, sold it with 290kmi on it... that car also idled slightly rough... and got to be pretty bad when you "lugged" it in reverse (manual tranny). It never seemed to be a major problem though, it always had state inspections done at Honda, and they test drive the cars, they never said anything was wrong with it. You may want to look into adjusting the idle though... as far as I know there is an adjustment screw somewhere on the throttle body.

My mothers old car (91 accord SE) always had a slightly abrupt shift to it when putting it into drive... the transmission was just not super refined and had fairly stiff shifts. As far as I know, all the 4th gens were like that... 3rd gens were even worse.

For the radio... try going to a honda dealer (you have to go so you can prove you own the car) and I believe they locate the radio code by the VIN number. People say it is on a sticker somewhere in the car... but that is VERY RARE!

Good luck with everything.