hi, i have an xtm mammoth, which is very similar in design to the xterm. i have to say, i love my truck, its great. now on to your questions...

the factory settings (engine?) are good for break in, but always double check. 3 turns out for both low and high are about right.

the motor is a ***** cat to tune. and it has great power for a rtr car. it is nice!

it has exploded diagrams, but no instructions since its already built. its realyl easy car to work on though

yes, u can change the shock settings easily