1.) Not really, because the rest of the car has 94K on it.
2.) I would ask for paperwork showing that they are the ones that installed and did the labor on the motor swap
3.) Couldn't answer that.
I honestly decrease value on cars that I see that have another engine put in it, because you as the buyer never really know if the work was done right and mileage on the body/engine is always different. Just my $0.02