Welcome. Actually my gauge runs just below the half mark under normal driving. It will run at half or just slightly above with the AC on in traffic or driving hard. You should be just fine as the others have said.

As for the spot mirror, on a hot day with the mirror in the sun, you can usually peel it off with your fingers. If not, take you time with a razor blade behind it. I have also heard you can use fishing line to cut the mirror loose.

You will need new double sided tape to reinstall.