Most model shops will be able to get you single pairs of springs. For indoors Blue front and Silver rear will be fine most of the time, sometimes we use silvers on the front if it's slippy.
Those Tamiya pinions wont work with the B4, you need 48dp pitch pinions; the 21t you already have wont be too far off on a 10 turn indoors.
A pair of front wishbones and shock towers should be fine for spares, the B4's a pretty robust car
The only oils you will need for most tracks are 30w, 35w and 40w. Most of the time you will be running 35w front and 30w rear, on all grass tracks sometimes 40w in the front works better.
What region will you be racing in?