Inserting pages from another pdf

I have a routine that is working well, taking pages form many various 
pdfs and inserting them into a new pdf. I have 2 questions though:

1. The original pdf's I am pulling pages from were setup at 5 1/2" x 8 
1/2". I want to put them centered onto an 8 1/2" x 11" and then draw 
crop marks over it. Is this possible?

2. After taking all the various pages and making my new pdf, can 
I "jump" back to a page and add a new text box on it? If so, how?

Thanks

Bill