For setup info i would have a read of these :
http://www.petitrc.com/reglages/BasicSuspensionTuning/
Or
hudy offroad setup book.
But theres no better way off fiinding out, than trying a change, but those will help you understand what does what.
as for your setup it changes from person to person. For me on high grip i run::
12.5k front diff (calm the twitchyness)
7k rear
42.5 losi oil front middle hole tower, outerhole wishbone
32.5 losi oil rear 2nd hole from outer on tower, middle wishbone.
(25wt oil seems to thin for me would have thought it would crash through)
is there anything that your wanting your car to do or stop doing?