BMW 750IL SERIES

I HAVE A BMW 7 SERIES I THINK ITS A 1989.
I HAVE SOME ISSUES. IT OVERHEATS AFTER WARMED UP, BATTERY RUNS DOWN IF LEFT FOR COUPLES DAYS, AND NEEDS TO BE JUMPED START
I CAN'T DRIVE IT NIGHT BECAUSE WHEN I TURN THE LIGHTS ON AT NIGHT, THE ENGINE SHUTS OFF.

PLEASE ADVISE WHAT STEPS TO TAKE. ENGINE SOUNDS GOOD.