I don't have a problem with any of your speakers but if it was me, I would go this route and in order:
1 - Upgrade receiver
2 - Mains
Honestly that is about it. The VP100 is a great speaker so are the QS4's so I think your fine there. The HSU is also good to go so no need to swap that out unless you end up in a huge room.
In reply to:
Would a 5x100 anthem amp benefit my current system.
If you had any other receiver other then a HK I would say yes, but the HK has plenty of power for what your doing now.
