Changes are listed out in detail in the ePO 4.5 readme.htm, but in summary there's quite a few:
Improved security for agent-server communication
Can now move agents between servers
Navigation redesign incl. Drag-and-drop
Can add menu items to the favorites bar.
Automatic Responses instead of notifications (more flexible)
Issues and ticketing through Service Desk or Remedy
The multi-server rollup reporting feature has been enhanced
The Queries system has been enhanced in several ways
Rogue System Detection has been improved
I'd recommend downloading the documentation and grabbing a strong coffee
I don't know the release dat for VSE 8.7i Patch 3, but if you sign up to the new SNS messaging service you can choose to recieve updates on patch releases and the like.
See McAfee support article KB67828 for more info on this free service.