Yes, most girls do finger themselves. N with different girls, it all depends how many fingers you use. Some girls can do 2, and some girls can use 4. But yea it's practically normal 4 girls 2 do that. like when a guy masturbates.
I don't...I honestly don't feel anything at all when I finger myself, and there are other things I can do to get off, so personally there's no need for ME to finger MYSELF. when someone else is doing it, that's a whole different story.
I don't know it's not that common. Well, my last girlfriend was Korean so their perception of sex is different, but still I know guys masturbate but my girlfriend had never done it before, and she didn't know how to do.