I've got a 2012 Honda Civic EX that the ambient temperature sensor and female plug came off of. I've just got two wires left.

First Question: What's the female plug called? I've tracked down the sensor itself but would like to repair the harness with the correct OEM-style female plug while I'm at it. I don't know what to search to find the correct part online.
Second Question: Does the ambient temperature sensor have polarity or is it just a resistor that I can hook the two wires up to on either terminal? If I can't find the right female plug, I'll just fix the harness as neatly as possible with my own connectors.

 

The connector has no specific name other than a "connector". Honda generally only sells the entire harness and very limited types of connectors.

For that sensor, aftermarket has the connector pigtail.

Napa autoparts carries one:





You even also purchased online from other aftermarket sources.

The wiring for each terminal are specific and should not be mixed up where they go. On your car, the Blu wire goes to terminal no. 1 and the Red wire to terminal no. 2; with an aftermarket pigtail connector, you need to splice the wires according to the correct terminals.