Man, save you Ksyriums. Those are nice wheels. Plus, the only way I'm aware of to convert to FIXED is by welding up the pawls inside of the freehub body. So.... (EDIT: didn't think of the fixxer....)

You have two options: Best method, buy a cheapo Formula Fixed/Free Hub, and build it to something like an Open Sport. Shouldn't cost you too much.

Or, get something like thishttp://pricepoint.com/detail/13456-2...ersion-Kit.htm to convert the Ksyriums to SS.

As for chain tension, you're going to want a tensioner, such as one of the ones herehttp://pricepoint.com/thumb/3-Parts-...arts-False.htm.