Guitar

Ok so I haven’t practiced piano. That’s ok; guitar has been calling. Tried to do some learning regarding modes. I know how to play them, but some questions remain:

1) When they are spaced out over the length of the fretboard, can it be said that: the X mode (major scale mode), is the same thing as the Y mode elsewhere on the fretboard using my Improv book’s idea as a guide?

2) So if the answer to (2) above is yes, and I’m thinking it is yes, can I substitute the Major pattern with a different pattern elsewhere on the fretboard, i.e., instead of only playing the major scale mode in a particular key, can I start in a different mode elsewhere on the fretboard as long as I use the counting technique?

3) What is a good procedure for figuring out what scale goes with non-diatonic chords in a progression? [It has something to do with the notes in the non-diatonic chord(s)]. 

Listened to some examples that I found on-line, and the ones I listened to were quite good!