[BrianG]

No and No.

Generally, you keep the "bridge wire" as short as possible while allowing enough length to route the wires where they need to go.

Doesn't matter which pack of a dual pack setup you hook up first. Until both are plugged in, the ESC sees no voltage at all (since they are in series). It's not like a Novak HV where the BEC is hooked to one set of inputs.