Rotor Bolt Upgrade
Lots of brakes come with Torx bolts for fastening the rotor. This can lead to problems on the trail or at the races it the correct tool is not available. Most of these bolts provide very little interface with the tool leading to rounding off, compounding problems.
Replacement Hex Bolts
M5(5x0.7) stainless steel allen cap screws should be used. 8mm long is perfect.
The best option for threadlocking rotor bolts is Loctite 242 or it's relative Loctite 243. Both are commonly refered to as 'Blue Loctite'.
Permatex® Medium Strength Threadlocker BLUE is fine to use as well.
For most users, safety wire is not truely needed. Loctite properly use will work fine. For the aspiring downhill racer, safety wire may provide that added insurance that nothing will go wrong at the worst possible time.
Safety wiring takes understanding and practice to get proper results. See: Safety Wiring