I'd go with fixation Rodeo bars over Origin 8, but not for any particular reason other than hating the Origin 8 logo and company.

You probably won't be able to fit the Sram 700 lever around the bend of the bullhorn. You'd be better with some cross levers(like these) or bar end levers(like these).

Most fixed gear/track wheels come with "flip flop" hubs. As long as at least one side is threaded for a track lockring(and the other is threaded for a freewheel), then you'll be able to put a freewheel on either side. Just read up and look at some pictures of flip flop or track hubs.