1. Not painful at all. You'd need a virtual server listening on port 443, and then assign an SSL profile to it which referenced the certificate and key.
2. SSL is offloaded to hardware on the F5, which means that it's a whole lot faster. Plus, all the certs and keys are in one place which is a lot easier to manage.
3. To terminate SSL between the LTM and the browser, you need the serverssl profile. Use the clientssl profile if you want to renegotiate SSL between the LTM and the webserver.
4. They can be imported. If your webserver can export a PKCS certficate, this SOL:
https://support.f5.com/kb/en-us/solutions/public/2000/300/sol2323a.html
...walks you through the PEM conversion process.
Hope this helps,
JQ