Allright, I have a few questions.

If you have a I-VI-II-V progression, and you change the VI (-7) to a dominant 7th, do you play the dominant 7ths corresponding mixolydian mode?

And if you change a Imaj7 to a maj7#4 would you then play its corresponding lydian mode as opposed to the Ionion that you would normally play over a Maj7?

I also have a question about Susb9 chords.

I know that typically a sus chord takes the place of a V chord. A Mixolydian mode is played over the V chord. If you change it to Sus you play the Mixolydian mode...correct? If you change it to a Susb9 do you then play the Phyrgian mode over it? Or is the susb9 built off of the phyrgian mode? And in the event that it is, do you then susbitute the susb9 for a V and play the corresponding Phyrgian mode?

Sorry if my questions arn't very clear, thanks to anyone who can help =)
First and second questions are correct. Last question.. *thinks* I believe you'd have to play the fifth mode of harmonic minor over it, I believe it's called frygian dominant. For example, over play E7b9 play Efrygian dominant (which are the same notes as Aharmonic minor).

Don't take my word for it though! Especially not the name
The "Popped Collar" Award(Sexiest)

The "Rest In Real Life" Award(Best Past MT Mod)