Yes I speed read (was taught the technique at uni) but I fortunately don't need to touch the pages. I just scan each line with my eyes - I used to use my finger as an aid years ago so I know what you mean.
I'd say you're fine to touch the screen if you have short nails and don't apply too much pressure. I prefer not to touch the screen as I personally don't like fingermarks. You can get screen protectors or if you had the Kindle in a plastic clear bag like a ziploc I think it's called then there should be no issue.