How can fizz book a heads up match against a specific opponent on Bovada if the identities are anonymous?

Through the mod that they are coordinating this through, I'd assume. One person sits at a table, the mod tells the other one to sit badda bing badda boom. Lots of easy ways to organize it.

Also, option 2 is also a TOS violation. I guarantee someone will report it if it happens.

Again, while yes it is a letter-of-the-law violation, it's ethically fine. Since both players are aware of what's happening and they are only playing against each other. Yes, it's possible that if some cheese eater tries to get /u/ripdunn in trouble with stars he may have his account/his buddies account suspended. Nobody should do this since, like I said, it's ethically fine but we know how trolls on the internet are. This is a risk he's going to have to weigh.