$1936

I think it would be nice if there was a way to edit it after you already submitted it because i sometimes overlook mistakes in my patterns and see them afterwards and have to redraw and resubmit the whole thing....
And i don't know if its because of my browser (Chrome V 50.0.2661.94 m), but sometimes when I use the fill tool in the alpha generator it doesn't fill the whole area but just up to where i clicked and it's a bit irritating..
+ if there was a way to have the colors fixed on the page, so you don't have to scroll up and down the whole time, or just an option to upload a .bmp or .png file to convert into an alpha pattern, it might be even easier to make patterns!

Whenever you make a mistake in a submitted normal pattern you can always ask a moderator to fix it. Via the 'report' button, or via a PM for instance.
It would cause problems in the checking process if the creator could edit a pattern after submitting, that's not a good idea.
Alpha patterns can't be edited by us, so you still need to remake these yourself, that's true.
The other things you mentioned will most likely not be fixed anytime soon. Our webmaster is the only one who can do that and he's been working on a whole new site/big update for years now. He is not going to change anything here now.