#1
Alright so for example if you're playing like and E, or A blues deal. Generally I would just solo in that key and that blues pattern, the usual, but are there any other keys you could solo in that would be "correct" I guess.

I mean I don't really need a big technical explanation since I'm not that great with theory but like if there was like a chart or website or something that would be sweet. Thanks guys.
Amps:
Fender Hot Rod Deluxe
Fender Champion 110

Guitars:
Fender Strat - HSS
Takamine: EG544SC-4C
Kay Acoustic

Effects:
Morley Bad Horsie II
ElectroHarmonix Big Muff Pi
Boss BD-2
#2
If the key is A major/minor, play the A major/minor scale. You are not restricted to those notes, but using all twelve tones effectively is something can comes with years of study and practice.
Someones knowledge of guitar companies spelling determines what amps you can own. Really smart people can own things like Framus because they sound like they might be spelled with a "y" but they aren't.
#3
When I solo over a A blues progression, I use both A and E minor pentatonic. There are many common notes, as you can notice by the "combination" of E minor and A minor pentatonic at the 12th fret, of course you don't resolve on the same notes as you would when soloing in E.

So as a "silly" rule I use myself, go 3 notes down, and you can use that minor pentatonic scale too. Haven't delved into the major pentatonic yet so can't say anything on it really.
My gear:
-Gibson Les Paul Studio
-Fender DG-11E Black (Acoustic)
-Marshall AVT50
-Cry Baby "Wylde Wah"
-Roland RE-20 Space Echo