#1
So, now that I've educated myself on creating chords and scales for each key, I'm wondering if it'd be worth it in the long run to go ahead and memorize every scale for every key, and practice every chord change within each key to where it's a muscle memory that's easily replicated. This seems like an enormous task to me, so I don't really know. I don't want to spend months getting to my eventual goal point if it's not worth it. Do you guys think it'd be worth doing now, or should I just wait until I need to do it for soloing over certain keys etc?

Also, for legato. Is it worth it to continuously change up my legato practice methods (fingerings, etc), or will my finger strength+speed increase at the same rate regardless of what I'm doing? Right now I pretty much just pick parts in the G major scale that span the whole neck and play them up and down as hard as I can each way to work on legato, since I find it pretty decent for stretching and I've got it memorized already anyway. But would it be worth it to change what scale I use every once in a while, or go outside scales and do random licks, or something along those lines? I really really don't want to be wasting legato practice if I'm doing something less than optimally.
#2
Most of it's going to be the same from key to key - the same chords barred up or down, and the same scales moved up or down a few frets. Guitar's about the only instrument where it's not really any more diffiuclt to play in one key vs. another as long as you use barre chords.
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#3
Don't bother learning the notes of scales, just learn the intervals. And don't worry about learning all the scales and all the chords. Just learn when to use minor chords vs major chords and when to use diminished etc. All that add9, #13, b11 stuff just refers to the interval and note of the scale that the chord is based off of.

As for legato, it's always good to use alternate fingerings, different sequences and stuff like that just to confuse your fingers a bit and get them loose and keep them on their toes, so to speak.
Quote by Geldin
Junior's usually at least a little terse, but he knows his stuff. I've always read his posts in a grouchy grandfather voice, a grouchy grandfather with a huge stiffy for alternate picking.
Besides that, he's right this time. As usual.