-Yes, they are compatible with each other.
-SATA drives do not have a "max" per se, but you'll be limited by the largest 2.5" sata drive you can buy.
-DDR2 and DDR3 are not compatible, also, your laptop will use SODIMM's incase you don't already know that.
What is SODIMM?
Is it worth it too upgrade my laptop?
what form factor am I looking for probably 2,5 inches?