Ok, not to be a grouch, but do you really have to post the same thing 3 times? I can understand a double post on accident... but 3?
1. Putting truck tires on the XP wouldn't really be recommended because it adds a lot of extra strain on the transmission and seeing as how those gears hold up you'd be going through them real fast. You'd also be more prone to break things because of the extra weight of the tires. One more thing, you'd probably want a better servo to do your steering.
2. Glow plugs don't really have anything to do with keeping the engine cool. Although they do fix any radio problems you might be having. (Not really...) But anyways the cold hot specification of a glow plug pretty much relates to how far into the cylinder the plug goes in. A cold one doesn't stick in very far and a hot one is generally longer and goes in further. You'll probably need a new glow plug after your done breaking the engine in if not sooner.
3. I don't know much about these so i'll leave that to someone else.
Welcome to the forums, and please ask as many questions as you want... just not the same thing three times