Skybone

You could always just plug the preamp pedal into the Effects Return of your amp, as it simply bypasses the amp's preamp and puts the signal into the power amp. I use a POD Go into the Effects Return of an Ashdown combo, works for me.

Guns of Navarone - The Skalites

Depends on what you would call "cheap" really. Under £20, you can't beat Warwick Red Label IMO. Between £20-30, you get a lot more choice, that Markbass deal at Andertons is tempting, Elites are always a good bet, Rotosounds are a solid choice. You can get D'Addario's at about £28 from their Amazon store (Pro Steels are my go to strings at the moment). Google searches are your friend here, shop around, buy in bulk for better deals etc.

Behind the Wall of Sleep - Sabbath

Going to be coming along when you play Inverness in April.

That Epi is cool

Other than the bridge / saddle / mute of the "original" 4001 / 4003, and the twin truss rod malarky, as have been mentioned elsewhere, something else that could do with changing is the height adjustment of the neck pickup. The scratchplate is a thick piece of plastic, so the neck pickup can't physically be set more very high, even if you take the springs off (I have). It'd just make it a bit easier resting my thumb on it.

Get the Funk Out - Extreme

Never tried one, really fancy trying out a Czech built through neck, but that could be dangerous!

Nineteen - Paul Hardcastle