Middleburn Oilesr are quite, quite useless in my experience, XTR cables are good, but you may need to buy some extra outer depending on the cable runs on your particular bike – they’re also easier to fit than the Gore ones.
It’s easy for me to say, but I think you’re making a bit of a mountain out of a molehill on the adjustment front – make sure you’ve got access to a decent set of cable cutters btw, trying to cut cables down with standard pliers will be hopeless. And as above, the Park Tool web site has comprehensive ‘how to’ stuff that should see you right.
How do you keep your bike shifting cleanly if you don’t understand cable adjustment btw? [sorry, I guess the point is that you don’t…]
As far as cleaning in situ goes, slacken off all the adjusters – maximum clockwise turn to stop and you may be able to pop the out cables out of the stops, move them along the inners, clean the inners, get some lube inside the outers etc.