My V100A has not been affected by any of the power lines in my area, including some high-voltage interstate transmission lines. That doesn't mean it can't be affected, just that I haven't seen any problems as yet.

The mounting kit should come with the computer. The compatibility statement is probably intended for users who will use one computer on 2 bikes, and so will need 2 mounting kits. I don't think the standard mounting kit will mount to a stem, but the manual for the computer is available for downloading from http://www.vetta.com