Question about: Upgrading to LR4 and adding hard drives

I am going to upgrade to Lightroom 4, partly because my latest ultra-compact camera's (Oly XZ-1) raw files are not supported in LR2. Also, I am nearly maxed out on my main HD, and am adding a 2 TB external drive with to archive older image files and free up room on my main drive (images are also backed up on another 1TB drive and a third drive at another location).

Anyway, I was wondering about a couple of things

1. What is the Lightroom-friendly way to move files from their original location, and will I have to re-import all of the ones I've moved?

2. Should I install LR 4 and then move the files, or move the files first?

Any other advice on how to make my life easier here would be appreciated.

Thanks,
Kevin