as above really how different are the wiring looms, or i imagine it would be easier to stick a pd 150 or suchlike turbo onto the non pd 110, instead of a complete swap, any thoughts

PD150 turbo is a relatively easy job - bit of fiddling to make the boost hose fit, but otherwise not much different than changing a turbo. Bigger turbo is wasted without bigger injectors though. PD130 has a totally different head and fuelling system (along with injectors, internals etc.), so I'd assume the work required would be greater than that for a complete engine swap!

Depends on what the final target is. A 110tdi should be tuneable to about 180bhp for c. £1500, although the clutch won't like it.

Probable easier and chaeaper to sell your car and buy one with the engine you want fitted. Less hassle to insure as well.

It's a very different beast I think the block is the same but the head and everything else is different. Plus the ECU, fuel pump.

IIRC correctly you look at changing the engine you also need gearbox, drive shafts, hubs and discs as they are all different.