[Hop-Head]

Hello, I see some talk about specific gas pressures for "domestic" beer at temp. Why is this important?

I have a converted refrigerator that keeps my local brewery micro-brews (IPA mostly 8%ABV)) around 36F. I adjust the CO2 to get a nice medium-slow pour. The reg is set around 12-15 psi.

How do I tell if I'm NOT at optimum pressure/temp?
Is all this about "foaming" problems?
If my beer's cold and my head is perfect, should I even worry about altitude, temperature and pressure settings?

Thanks,

Tom