Damn Hide! You're killing me! Haha. Ok here we go...
Yes he has contributed to the songwriting although this is about 90% Mark as far as music lyrics and melody go.
Yes you will hear Mark's voice quite a bit on this album.
Yes the singer will play rhythm guitar at live shows on a few of the songs allowing Mark to go "fully sick".
Yes there are plans for subsequent albums and yes Brian and Flip contribute to the songs in the later stages.
I am very sure the boys will end up in Australia at some point. They all love Australia.
Yes Mark plans to do his hardcore metal project at some point in the future.
My personal opinion is no but we'll see how it shakes out.
Sorry I cant answer this last question as Mark is rehearsing right now and I wouldn't want to hazzard a guess without asking him.
Michael