You can carry any pistol you want with your CPL, you do not need to qualify with anything. I used a P22 for my class.
As for capacity, I don't think anyone cares. I've never heard of anyone being prosecuted for carrying more rounds then stated on their green card. considering the vast majority of auto-loader pistols today can accept a variety of magazines, I don't see how it would even be enforceable.
I carry a G19 which my green card states is 15 round capacity. I often carry a 17 round mag instead. I did something similar with my XD. You don't need the mag to fit flush, either...I could carry a 33 round mag in my Glock if I felt like it. Might be a good idea not to do that just to avoid getting hassled...but there's nothing that says you can't.