1.)  It is normal for the battery light to be on after start up if your
engine's RPM is not high enough. It is because the Bosch alternator unit
needed to rev. pass 1200rpm (I think) to kick in.

2) Idle problem. If the idle is OK after engine is warm but can't keep the
idle when cold, and the engine runs fine (not too rich, not too lean) when
warm, check to see if the idle control unit (part# 251 907 393B, it is a
small black plastic box located behind the rear passenger side turn signal
housing) is OK. Check the wiring to that unit is all tightly connected. 
Another possibility is the idle stabilizer (it sits on top of the engine). It
is basically a solenoid. So check if there is power to the unit and see if it
moves when power is applied.
       
Good Luck