Looking over your profile now that I've gotten some sleep, I realized a lot of the info wasn't showing and went in to fix some of the coding. Using two ' instead of " for height somehow threw it off. I also straightened out the list of family members the other night as well. To note, if you want her to be 5'1" like she was before on the profile, you just need to reduce the weight to match, that's all. Initially, I only saw the weight thanks to that oddity you see. Asides from that, I suggest you make a page for yourself; it's currently the red-link on top. You don't really need to put much of anything in there though, but having a profile page on the wiki comes in handy for keeping track of your characters.
I also must comment that your artwork looks quite nice; how long did it take for you to do that?
Moving on to your questions though. Typically, RP takes place in plots on this site, but yes, there are more informal methods. You have the option to have an Open RP, which you can be the Game Master of if you'd like - typically though, they're considered soft-canon since people tend to be still learning the ropes there. Alternatively, you can try finding someone to do Joint Posts with; if you're not familiar, it's essentially using something like Titanpad or other so several people can write at once.
Also, keep in mind that it's not unusual to join more than one plot here at this site, so if you see any others that capture your interest, I suggest you go for them as well.
EDIT:
Tugs on @Sigma