I'm just finishing up adding outlets to the front and back of my house. I have it arranged such that a new line runs from the panel to a junction box, where it T's off to feed the new outlets. I understand that I need GFCI protection on this circuit, but I'm not really familiar with the ground fault application. If I were to add a GFCI outlet at some point between the panel and the junction box, would the two branches coming out of the junction box both be GFCI protected?
LOAD terminals have precisely one purpose: to attach downline wiring that will be in the "protected zone" of the GFCI. Only that should be attached to LOAD; all else goes on LINE.
So yes, any GFCI device can protect a downline that is properly connected.
If any hot or neutral wire in a cable is attached to a LOAD terminal, then all hots and the neutral must be attached to LOAD. The only exception is dual-neutral (12/2/2) cable where you really know what you're doing.
Ground must bypass the GFCI (bootlegging ground off neutral will defeat the GFCI protection). So for instance if you have an old 2-wire groundless downline, people who want a 3-light tester to read normal, will often bootleg ground off neutaral to fool the tester. Anything like that must be removed, or the GFCI won't protect you.