i was wondering if this will work?
i have led's in my footwells ATM that lead in to a swich its ground to the body of the car(and powered from the batt) i was thinking if i ground the swich to the door lights will they come on when open the doors?
if so how meny can i run iv got x4 72cm led strips was planing to add 2 more for door lights

Yes, if you use the earth from the door switch, it will become the switch for your lights.
LED strips are pretty efficient, you'd run all 4 pretty easily.