How to determine the "doneness" of salmon? I, like most people, prefer fish to be cooked correctly. For salmon, this means soft and velvety (but warm) in the center -- what I would characterize as medium rare.

I consistently overcook for two reasons: one, fear of bad stuff and two, because I am guessing. What are good rules of thumb for telling when it's medium rare?
Press the salmon. The less cooked it is, the softer it will be. You more or less just have to learn by touch.

Broad rule of thumb: 6oz (flat-ish) portions of salmon take about three minutes to sear one side in a hot pan, flip, throw in a 350 oven for 5-6 minutes.

If roasting from raw, should be 11-13 minutes in a 350 oven.