BE 2010 R1 to R3 upgrade

I have to upgrade BE 2010 R1 to BE 2010 R3, and I have a few question :)
Sever : 2008 r2 std,
Agents : 2008, 2008 r2, 2003 r2, 2003

1. Reboot is required on servers or not ?
2. What about agents? Do we need restart?
3. How to check if aofo is installed ?

Thanks a lot for Your help :)