be careful on how heavy the shock oil is and pay attention to the pistons; using a high wieght oil with 1 hole pistons will blow out the shock seals and will NEED replacement-no way around that a good truggy weight is around 60 or 70 weight if you use losi or other silicon based oils....
as for diff. oil a good starting point is 20k in the front and 30-40k in the rear if you run on a loose track, but if theres a lot of traction 10-15k in the front and 20-30k in the rear. fyi those are just starting points not definates so your truck may need some tweaks, also be sure to shim the diffs. properly this can help with differential traction by not allowing them to completly unload under power and gradually power up the wheels.
the tire ballooning thing is just because your truck has a center diff. any true truggy has one and all have front end ballooning unless you really tweak your truck...ex. my mammoth st pro has a center diff. and balloons the front and thick diff oil in the front DOES NOT stop it so dont go too thick to try and prevent this... its just truggy nature