How to bring a digital input pin to high state?
To get at your question about if you can plug power directly to the pin with no resistor and have it always be high... yes, that does work.

When you have your microcontroller set to input mode you can treat the pin like there is a very large resistor inside. So using ohms law, V/R=I with V=3.3 and R=very large, lets say 10megohm gives you a current of 0.33 micro amps. The inputs are designed to act like such a high impedance so that it has a very small effect on anything externally.