1) There's not really a good way to do it. The binding process requires a lot of pressure on the pages, so any glue would get forced all over the place. You could scan and reprint pages if it's only a couple, but with most Marvel books (no matter how old or new they are) it's so many pages that that doesn't end up being very cost effective either.
2) Yep
3) You can't have any single pages if you plan to have it smyth or handsewn. Even if you leave part of a page, that's not enough. If you want it oversewn you're okay to remove back covers/non-story pages just like you would if you had the book bound DFAB.