2002 BMW 325 sluggish transmission

I just bought this car this week, and I noticed yesterday and today that when it was cool and first started up the car did not want to move unless it was revved up a good bit, once it started going yesterday it was fine. Tonight when I stared it up the same thing happened, and then a yellow light came on in the dash, it appeared to be a low fluid light, is this the autotansmission light and would this cause it to be sluggish? By the way yesterday was in the 60's and today was in the 70's. If it is low what type of fluid will suffice and must I only get it at bmw or is there a certain spec I can get elsewhere?