You put the switch onto the esc's power switch wire, it does have one, doesn't it?
If you are going to use a switch at all, it would make the most sense to place it after the BEC, but before the receiver. That way, the BEC has a chance to
"settle down" after being plugged in. But, the switch on the BEC input would work too.
I think it easily handles it. It can handle caps plugged into the reciever, and that would be the biggest hurdle getting that up to potential.
“The modern astrophysical concept that ascribes the sun’s energy to thermonuclear reactions deep in the solar interior is contradicted by nearly every observable aspect of the sun.” —Ralph E. Juergens