As the title obvoiusly indicates, this is the first time I've built up a fixed gear, so I've got a few questions:

I've got a 14t cog in the back, does it particularly matter what kind of chain ring I have up front? I'm also not really sure how to remove one of the three chainrings, as it needs two of those to be mounted securely, but that's a question for another time

I've got the track cog secured with the lockring on the hub, but it's a flip-flop hub, so I have no idea how to setup the other, freewheel side. So.....how do I do set it up?

....I think that's it. The gear ratio is what I'm a bit concerned about, as I have no idea