40 gig ps3 parts for a 60 gig ps3, is it posible?

May be...

I have a 40 gig ps3 that's not working "yellow light of death" and a 60 gig that is working. If for what ever reason my 60 gig blue ray player burns out or just stops working can i replace it with the 40 gig?? and if so what else can i use off the 40gig?

Yeah, you can. Your 40GB is basically a back up. If you encounter YLOD on the 60GB, your 40GB will come in handy.

Yes, theoretically, you can. You can probably use anything but Emotion Engine replacement, 3 or more USBs, or Media Cards.

Probs not as it wont have enough power