1. Nice catch. I've fixed it, but it may take me a while to get round to putting up the corrected version.
2. What you're seeing is that the trapdoor "wing" contains two colours, and the pixels of these happen to be present in different proportions in the last two frames because of the way it opens at an angle. It's exactly the same in all the styles except Pink (which uses a different, ten-frame trapdoor animation), but most noticeable in Column because in this style the two colours used are furthest apart. Nothing to fix there.
3. True, but I like that graphic and I found the digits readable enough for it to be usable. I'd rather not change it, but I'll consider it if you think it's a big problem.
4. I'll see what I can do about this one when Jayelinda visits the week after next -- she's the Photoshop expert. I think what's happened is that as I've made the lettering so much darker, the border pixels, which are meant to be very faint to give the impression of a nicely rounded curve, have become darker than they should. I know it's annoying, but it wasn't easy to get the lettering to be the dark colour I wanted it. One improvement I've already made -- there was a pixel in the "9" that should have been black (and hence revealed the background) but wasn't. That's made it a little bit nicer to look at, at least!
5. Ah yes, the infamous blank line glitch. For some reason Cheapo automatically inserts one when the line is a certain length; adding a line break won't help. (Actually, I'm pretty sure there was one anyway; I always use manual line breaks to prevent words being split between lines.) I've taken out the word "then", which is the best solution I could find.