By wiggling the front wheels with the steering held over all the way. If you go too far one of the wheels won’t wiggle because the linkage will bottom out, servo likely will make a little noise too, back off the dual rate a touch. Repeat for the other direction. Check it through suspension travel, front up and down, to be extra safe.
If your radio has End Point Adjustment or Travel feature, first turn dual rate all the way up, use the epa/travel feature instead for both directions. (EPA is a very desirable feature when/if buying a new radio)
Yes to the completely installed and connected.