In Re: to corrosion:
I haven't read the details of MIL-STD-889B in a very long time (okay, not ever), but according to Notice 3, zinc and aluminum are compatible. I believe this means that they do not corrode at all when in contact in typical motorcycle type environments, but it could also mean that the zinc, being more anodic, will sacrifice itself to protect the aluminum.
Regardless, the more important consideration is if something does corrode, what part do you want to deteriorate? The difficult, and potentially expensive, to repair threads in your aluminum engine casing, or a relatively cheap and easy to replace fastener? If you use stainless fasteners, the aluminum is the one that degrades. You'll eventually need to heli-coil the sumbich, which is a whole'nuther can of worms.
In order to protect from galvanic corrosion when using stainless and aluminum, you'd need to either (A) create a barrier around the joint from any electrolytic solution (including airborne moisture) on both sides of the joint (the head of the fastener and the opposite side if its a thru hole), or (B) provide an electrical isolation between the two metals such that they are not in electrical contact at any point. Thread lube will not do this unless it is a zinc based anti-seize, which I highly recommend (for nearly any fastener in aluminum).
Zinc plating is what I use. If I forget to apply zinc dust anti-seize, no big deal. If you use stainless, try to remember to use zinc anti-seize, otherwise the aluminum threads will corrode. How long? Depends on where you live, how your store your bike, the average temperature, humidity, salinity, acidity of local rain water, etc. Maybe a few years, maybe a few decades. Take it or leave it.
