Ballscrew lead question

I'm finally ready to buy my ballscrews and nuts.

My question is about screw lead versus machine accuracy and
repeatability. I'm seeing a lot of surplus ballscrews available lately
with a .250" lead (4 turns per inch). Considering that I'm going to
gear down with pulleys anyway, is this pitch OK or am I better off
waiting for a the rare .200" ones that come around every so often?

Also, if I see some metric screw where the size is perfect, but with a
metric pitch... Is TurboCNC and/or EMC able to handle odd pitches like
this and not choke doing the math while interpolating?

Thanks
David

P.S. - I have a Bridgeport clone (actually a little smaller) and I'd
like it to repeat to at least to .001", and I don't care if my rapids
are not blazingly fast.