3) make darn sure you know what kind of malpractice insurance you have covering you! A mistake here could do you in financially. Our institution had an occurance based med-mal policy (which includes "tail" coverage). They recently switched to a "claims made" policy which does not include tail coverage. This means if you get sued after you are no longer moonlighting and the moonlighting policy has expired, you have no coverage for the prior acts. Buying tail coverage after the original policy has expired, is expensive, as in about what the original premiums were. Or you might have to buy prior acts coverage with your first policy out of residency.
The cash might look nice in your pocket today, but there's a huge risk to much greater earnings if you don't play this one right.