Stick to a tooth count that divides into 360, Chuck. As has already been said, 80T will result in it being hard to keep track of your dial. 60T would be a good choice if you wanted to include a detent in the rotab for simple direct indexing, where it would work for dividing circles by 2,3,4,5,6,10,12,15,20 and 30. Out of all the numbers you are likely to need in direct indexing, only 8 is missing.
As to previewing posts, I think that normal operation is to compose your post, then click Preview and scroll up to see the preview pane above the toolbars containing all the smileys, dancing girls etc. You can't amend in the preview pane, but can scroll back down to the "compose" pane and make any adjustments before finally clicking on Post. Forgive me if this is too elementary, but are you scrolling back down again after previewing?
Andy