1999 BMW 520 520i touring elec problem

Hope somebody can point me in a direction with this problem. Symptoms are:
- airbag red warninglight, bottom right of dash permanently on since buying it july2008.
- since june 2009 following symptoms:
- abs and danger warning light permanently stayed on.
- speedometer intermittently goes on and off - when off, cruise control doesn't work.
- twice the car got absolutely no power when trying to start. Lock/unlock didn't even work. Battery checked twice by ANWB (dutch AAA). They measured battery twice, it is fine. After jump start it works fine again. Until the next power outage.
- car stalls about 2 times everytime I drive in city traffic, always in 2nd or first gear when driving slow or stopping for a traffic light.
- oct 2009 had battery read: when idle, voltvalue is 14, when car is turned off, reading drops gradually to 12.2.
Pls let me know if you have a suggestion what it is. BMW garage here charges 100bucks just for making an evaluation appointment, thats why i'm trying like on this forum.
pls mail me at QRT85@hotmail. Com. Thx for your input,
Quentin @ Amsterdam