I've heard you need to get new top mounts as well. Can anyone confirm this? I don't know much about it.

Not really necessary, esp as your car is very low miles. I'd replace the top mount bearings though, they are common to fail. Infact mines are groaning every now and then just now.
 
This may be a really stupid question but how many drop links do I need? I'm installing JOMs and mondeo drop links. Do I need 2 or 4 drop links