I'm thinking of swapping all my current gear onto a new frame. should I change anything at the same time? new gear cables etc etc?
Take peoples advice and buy a fully built up FS bike.
I bought a FS bike when the cost of replacing parts on my HT became silly ie the fork was passed it etc.
I wish now that I had kept the HT in working order so that I could choose whether to use the HT or FS, you will miss the HT if you strip it off all its components.
New gear cables are always a good idea, just to get it nice & crisp.
When I took the bits of my old FSR & put them on an Inbred I needed a new BB (as the old one was knackered), new front mech (the old one wasn't compatible), new seatpost (different seat tube diameters).
I think they are the main things to consider, as well as the headtubes and whether you need a new headset.
I also got new shifter as the old ones were very tired & a new saddle as the old one was getting shabby.
Only what's needed - rr gear cable top of that list usually.
Only replace when worn out!