Mkay well vertical dropouts do complicate matters
http://www.eehouse.org/fixin/formfmu.php
This can help you calculate a "magic gear" which is a gear that will have good chain tension without the ability to adjust,
http://www.blueskycycling.com/view_p...eProductSearch
heres a half link that can also help.

okay 12 speed makes more sense, you will most likely be able to keep your BB and crank then.

you should figure out the spacing of your frame, which can be done by measuring from the inside face of one dropout to the other.

This will determine which wheel you want (or if cold setting is necessary)