EOD should be fine just switch sides. Who gives a shit its your ass. its not going to be like a huge hairy birthmark just a little darker skin. I like my 22.
i use 25g for everything, but for the glutes it is a pain (no pun) because of how long it takes to inject..
you can switch cheeks, but i try not to hit the same muscle more than once a week, at the minimum 4 days..