To answer the bullhorn question, I like bullhorns on my fix because of the lack of hoods. On my road bike I'm generally on the hoods so it's a natural transition.

As for gearing, with the spacer route you have tons of options for gearing. I doubt your first choice will be your last, play with it and find what works for you. You will probably need shorter stack bolts, look for BMX ones.

Don't bother with a tensioner, they suck and you don't need one with your dropouts.

Good Luck and report back.