I can answer part of this. Yes, it IS possible to perm curly hair. I have had mine permed before, but to loosen the curl. I have rather tight curls which tend to frizz, and my hairstylist recommended a perm. She's a curly too, and had done them before, so I tried it. It did loosen my curl, as she said, but I still had to use products to get the look I wanted. It definitley didn't make my hair wash and go.

As far as making curls tighter, I don't know if a perm will work for that. Hopefully someone else will chime in.
3b/c normally, 3a/b in the winter