Hi, I will add to your confusion!
1) Dont know your program, I use Paint Shop Pro 9 and love it, also any of the Adobe Photoshop programs are excellent too. (e.g PSE4, PSCS etc). Get the best you can afford and that your computer can handle, they are very hungry for memory.
2) Prints depend on a lot of factors, like resolution and printer, the above programs will enable you to make great prints.
3) I use Kodak matte heavyweight for scrapbook pages, sometimes I use the satin but I am not fond of glossy.
4) Depends on what elements and papers you choose, you can add texture and dimension to most things if they havent already got it.
5) You could add elements to the digi, but remember they may dent the pages underneath, but I guess this could happen with regular scrapping too.
6) I print my layouts to fit 8x8. The 12x12 kits are easily resized to fit.
Hope this helps a little.