Even if the Rp is a sex only design, I still like to have a general idea of personality and whatnot, makes the experience more fun imo. I'm also not very adamant on the will not's and will probably accept the idea if it sounds interesting. With the exception of scat, that will always be a no.
I usually prefer more submissive roles, but on occasion I can get a bit wild if my muse is leaning that way.