#1
I've been doing some serious reading through the theory sticky and I am extremely happy to be able to say that this stuff is actually starting to make some sense. Scales, chords, it's all starting to make more sense now. I have a question. The sticky mentioned "Natural minor- minor, m7, m9, m11, m11(b13). It fits well into minor chord progressions and works in almost any style of music. You'll find this scale mostly in metal, rock, and it fits over power chords in a rock/metal song. Ex. Using each root's minor scale in a G5 D5 E5 A5 progression works in a rock scenario." What I don't get is the part about where it says use each root's minor scale. Why would you do that over that progression? Wouldn't that be jumping in and out of key if you changed from G minor to D minor etc? I have been under the impression that if the song was in G minor for example, you solo in G minor and don't jump around to other minor scales. I hope I'm able to make myself clear to you guys. Thanks for the help.
#2
you can do either. because 5th chords only contain two notes the root and the fifth, and all those chords contain just one interval (a fifth) it's easy to fit different notes / scales over the chords without causing any harmonic clash.

You could play a G minor scale over the progression in your example, and it would sound fine. the G5 chord contains G and D, which are both in G natural minor (root and fifth). The D5 contains D and A, also both appear in the G scale (fifth and minor seventh). The E5 contains E and B, which are actually more friendly to G major, but if you just play G, C and D notes over that chord, you could still remain in G minor. The A5 contains A and E, which can also work in G minor.

What you will find is that certain notes will work better than others over the chords. In almost any situation, you can stick with root, fourth, fifth and seventh notes and you'll never sound "bad." The thirds and sixths are the ones that can be dissonant if you play them over the wrong chords, but you can always remember this: if the note you're playing sounds bad, move it one fret in either direction, and you'll be in good territory.

and of course, you can always choose to match the scale you play to each individual chord, but you have to REALLY know where you're going with that idea, or it'll sound too awkward and take the listeners focus away. People often like to hear one instrument remain in one scale while the other instruments move around a progression. it sounds pretty standard, but it's standard because it works.
#3
You don´t have to change the scales.For example, If you´re in thev key of A minor and play A5,F5 to G5 play the A aeolian/natural minor scale over the whole progression. Just because the the chords changes doesn´t mean that you have to change the scale.
#4
I think G5, D5, E5, A5 is just an ugly chord progression lol. But I digress... Gmaj pentatonic scale sound way better than "using each root" over that.

Considering the notes you have (G,A,B,D,E), it would be perfect.

The reason I say it's ugly is because it doesn't sound like it resolves.