yes, the suspension links should just pop off the ball joints. I usually use a broad flat-head screwdriver with the tip covered in a rag or something to pop them off.
As for how to get to the diff, it depends a lot on the specific vehicle, but in general you're going to have to remove the transmission assembly. I assume you bought a RTR, but you should be able to get ahold of the assembly instructions from the manufacturer's website. If not, just start taking it apart until you get there, but make sure to keep track of which screws go where, etc.