RE: RX Ant. Length
Looping the wire, as if wrapping it around a tire, with the start and endpoints on the same plane (imagine laying the wire flat, then rolling it up on the wheel) would indeed cancel.
What we're talking about is a loading coil, like in a coil spring, where the endpoints are along the axis of the coil, and none of the wraps actually cross each other.
Yes, there is some signal loss compared to a straight 1/4 or 1/2 wave whip, but the load and SWR would still be correct.