Can this calculation be used for stocks and options?

Evaluating position performance can be used for both stock and options positions.

Can this automation be used to open a position?

Yes, you could use a position recipe to precede an open position action.

When would I use "Position Premium Increased" vs. "Position Premium Decreased"?

When selling options, decreasing premium will result in a profit. When buying options, an increasing premium will result in a profit.

Can this be used for both profit targets and stop-loss management?

Yes.

Can I combine different position performance criteria into the same automation?

Yes.