Hello from a Land Roverer in UK

[jayartibee]

Hi all
I am lucky enough to have a Land Rover Series/Defender hybrid with a D24T sourced from a Volvo 740.
I've joined with three initial questions.
a) is it possible to convert the pulleys to poly-V? My alternator belt seems to scream a lot when cold or under load and I don't want to make it any tighter.
b) how do I adjust the idle speed?
c) last year I replaced the front four glow plugs. (Back two very difficult to get to) One of them was a pain to get out and indeed seriously damaged the thread. I am not confident about next time. Can I tap out the hole to take a larger plug?

I hope you guys can give me a hand.