Thank you for asking again; it was cut off last time and I was hoping you would. :)

The size of the paper is up to the artist, but the proportions between width and height have to match the format that you want the finished comic page to be in. So if you want to print your comic as a 5"x8" book, you can draw on 5"x8" paper or you could draw on paper twice as large (10"x16"), etc. I am drawing a project right now where I have multiplied my specs by 1.75! It doesn't matter as long as the paper is proportional to what you want the comic to be in the end, and you can resize your pages correctly in Photoshop or some other program.

(To make things a little more complicated...if you have specs like bleed, trim, and safety dimensions, remember to enlarge everything by the same percentage when you draw on larger paper.)

There are a few reasons to draw on larger paper. It makes it easier to draw little details like eyes and backgrounds. If you have trouble drawing thin lines, shrinking your line art for print makes your lines look thinner (this is why I do it). In general, shrinking pages makes your mistakes less noticeable. However, the larger your paper, the longer it will likely take you to draw. Also, remember that you need a scanner large enough to accommodate your pages (if you do anything to your pages digitally).