The first question is something that i suggested and think is important. Basically, the letters themselves (like 'q' 'w' 'e' 'r' 't' etc) are very small within their button. Look at Opera, iPhone, Android, Maemo's default, the letters are very big on their square and this makes typing much easier.

If you can't create a skin, how about not having it change with each theme and just have a stock colour like grey?