i would repair before you start adding stuff like led's and rims. but a stereo upgrade is acceptable in just about any car in my opinion.
i would remove that rust and get that spot painted, get the correct color tail light, do a major clean up on the engine and interior if needed. i also noticed your right taillight doesn't have the red stripe on it, i would either add it myself or get one that does. also i would clean up headlight lenses, and after that start modding stuff = )
overall though its in good condition, a work in progress, just like all of ours are!
thanks for uploading pics though our cars are twins!