Rod Racer

Penrite Type F is very good, likewise Castrol TQF. I mention these 2 because both are very good in severe use (trans brake @ 4000 rpm flat throttle hold), as I can attest to, having used both. Do NOT use Dexron 2 or 3 in early Ford Transmissions (C4/C6), unless you like rebuilding them often. I speak from experience. Their pumps don't work well with the thinner fluid. I also change filter and fluid after the first 1000 km of use, regardless, as the new parts wearing in create some debris that can restrict the filter, and as mentioned, don't use the dacron filters.

No, it's not normal, but they are getting on and new replacement gear sets are harder to find. I had one years ago that was noisy, so I changed the filter in the pan and used Castrol TQF fluid, and bugger me if the noise disappeared, never to return. Make sure the correct fluid is used (TQF), NOT Dexron 2 or 3, it's too thin for the C4/C6 transmissions. If it whines at idle, that is usually a blocked filter and/or too light a fluid.

I'll do this on the XF's PS box to see if it comes good, only then will I replace it.

Like I said, have a chat with Crow Cams and/or Clive Cams, they might have grinds that are suitable to use with VCT.

The point of the VCT is to advance and retard the cam's timing to suit various conditions. Advancing cam timing boosts torque at lower rpms. Retarding the camshaft at higher rpms boosts power. This allows the engine to make more usable power over a wider rpm range than the standard engine. Using larger duration and higher lift cam(s) would cause piston to valve interference when the VCT attempts to do it's job. If you are looking for a lot more power, just lock out the VCT sprocket and use the appropriate cam to suit your needs.

Cam selection for a VCT engine needs to be carefully considered, due to the amount of camshaft advance and retard happening. Excess of timing duration and/or lift will cause piston to valve interference and a badly damaged valvetrain, cylinder head and pistons. I'd suggest you call Crow Cams, or Wade Camshafts and talk to them about this, rather than relying on info from the interwebs. They might have specific grinds to suit the VCT engine. Otherwise, perhaps converting back to non-VCT might be an option, considering your RWHP expectations. Good luck.