Hi mate, that is quite a series of questions/comments there, it would help if you can be more specific about exactly what you want feedback on.
Generally a twin plate clutch does have more bite/ is less progressive to use....there is a reason they are not fitted by the factory. So basically, that is something to learn to live with.
A clutch issue cannot be affected by revs, because once it is fully engaged it is either working (ie gripping) or slipping. So if you say it is not slipping then there is nothing further to look for with the clutch.
The clunking noise when first going under power is likely to be a worn or misaligned diff centre, or stuffed Cvs (or maybe uni-joints) in the tailshaft. I am surprised none of the mechanics diagnosed that because it is quite common. The fix is to replace or recondition the tailshaft, or if it is the diff it may just be able to be adjusted. Nothing should clunk when you put your foot down, it is the sound of something moving when it should already be fully engaged.
Finally, the drone is a lot harder (I'm assuming it is driveline not engine or exhaust). It could also be a diff problem (eg low on oil, or orn), or a gearbox problem, or even just noisey tyres. If it gets better or worse when turning a corner it might also be a wheel bearing. Hard to more specific than that without more clues