I'm currently applying VoIP QoS rules. I've created an entry for VoIP and its counting the packets, so I assume its working, I've also set the priority as 2. I'm just wondering, for the QoS to be effective, do i need to create a queue tree entry for the rest of the traffic on the router, or is VoIP now prioritised over everything anyway now its set to 2?

For prioritization I usually do interface attached queue trees rather than global-attached, since it is easy with global-attached queue trees to forget about some traffic.

Parent Queue Tree (child of interface, ex. ether1, rather than child of 'global')
- Regular Traffic (child of Parent queue tree)
- VoIP Traffic (child of Parent queue tree)

The parent queue tree needs to be programmed with the max-limit equal to the speed of the overall connection on ether1. The packet mark for the parent queue should be left unset - note this is different from no-mark.

The regular traffic child queue tree should be programmed with a lower priority (ex. '8') and made a child of parent queue tree. Packet mark for it should be 'no-mark'.

The VoIP traffic child queue tree which you have already created should use a higher priority and match the packet mark of your choice.