Hi Skrylle,
To remove the hexes, you can stick a slot screwdriver between the hex and the bearing and gently push towards the hub.
For the bearings, you can find tons of videos on youtube comparing bearings for rc cars. In short, if you just want to play with your car you should go for rubber sealed steel but if you want to compete ceramic is what you want.
The small shocks are approx 7.5 cm long (full length) and the long shocks are about 10.5 cm long.
The ball diffs are not too difficult to assemble, you can find the instructions in
http://www.retromodelisme.com/manuel...-r-kyosho.html
Have fun with your project.
Ubi