#1
Is it even necessary to learn the major scales if u can just use the relative minor scale for youre major root note? im basically asking if the realtive minor scales of a root note cover the same notes as the major scales of that same root note.

Ex:Would soloing in C major scales be any different from soloing in the A minor scales ?
#2
Yea you're starting on a differnt root note, so it will sound different. In theory, it is the same notes in the scales yeah, but they all have a different feel to them. Try it out and you will see what I mean.
#3
it matters how you're learning the scales. If your learning the relative minor scales based on note, then you'll be able to competently solo in the relative major scale without "learning the scale". If you're only learning the scale based on interval, you'll need to learn the major scale too.

How to tell the difference: Can you identify the names of the notes instantaneously of the minor scale in question for each fret in the scale? If you can, then you know the scale based on note. If you can only identify the fret numbers in the scale without knowing the notes they represent, you only know the scale based on interval.