In order
1) Sorta kinda not really. Licensing is one of the more complicated parts of the upgrade. You really really need to read the upgrade guide and the release notes and the preupgrade checklist. Basically you will need to have both the old license server for the v3 farm and the new serial number licensing for v4 already set up. You need to do some stuff on your vmware.com store account to get your licenses figured out and I suggest doing that ahead of time.
2) yes, again this is mentioned specifically in the upgrade guide. you will need to upgrade the vmware tools and that will require reboots fro teh vm's but it doesnt have to be done immediately.
3) remove your SAN cables before doing a fresh install so you don't accidentally end up overwriting your VM's on the san, read the Install guide and have backups just in case. you will also need to have root password, ips, gateways, dns fqdn's all written down so you can put them on the new server to match the others.
call support if you need specific help.. I have to go get dinner now :smileywink:
Hope that helps
Hanna