Adobe Flash on Haiku?

No you may as well consider flash dead. Even Adobe is abandoning it for HTML5 which haiku is slowly gaining support for.

There was a Gnash port that worked in Bezilla however support for the Bezilla plugin was dropped and Gnash now only runs as a desktop app if you can get it to run at all. It might be updated once haiku reaches beta or R1 I bet though to and Web+ might add support for it who knows.