1. If you end up deciding (as I did) that you can't write a diversity statement that is that interesting or meaningful or makes you stand out that much, I don't think it's a big deal to check the box you mentioned without adding a diversity statement. For Penn, I checked the box without adding the statement, and I'm not too worried about it.
I ended up writing a diversity statement about my Chinese background rather than about being gay, because I felt that the former had more effect on my life. I did grow up in a pretty homophobic (Chinese) society, but I didn't think I could write a gay-themed diversity statement without having it either sound like a sob story or sound generic and very similar to lots of other people's diversity statements...and thus not so diverse.
2. absy, is that your real picture? Are you a 1L? If so I wonder if you know a gay 1L there who I know from when he was at Yale College. I shouldn't post full names on this board, but let's see, his first name is Brad and his last name starts with an R...