Will this phototransistor circuit work?
Is the penny blocking the light or reflecting? Depending on what its supposed to do you might have it reversed. When the phototransistor receives light and conducts the FETs would be ON.

Except that you have a voltage divider across the gate: R3 + transistor + 1k, then gate, and then 10k. So you'd be lucky if your gate saw 2.5V in this config, which is a bit low to turn mosfets on. I'd use smaller gate resistors and a smaller R3.

Also I'd add a small resistor in series with the LEDs just in case..

p.s.: yes you can use 12V at these FETs gates. Both are rated up to 20Vgs.