i have just bought a second hand scott fx-2 g-zero and want too upgrade it?

i want to buy a new bottom bracket and new front and rear shock for my bike but cannot find the size of each or which forks or shocks or bottom brackets are an upgrade or best for this bike. can u recommend also which are the most vital upgrades to do first to improve the quality of the ride?! i have hayes hmx-1 brake discs also and would like to know if it is worth upgrading thses brakes or just buy better pads?