You and your mates need ta know
how to ask questions and then use your search engines
(no offence meant there mon, but hey!)
Googled "Home made bandsaw plans, free" with over 22,000 entries, granted not all about bandsaws but ya catch my drift eh, theres a ton of info out there its just a matter of spending a bit of time to do the searches, learn to ignore the obviously non-helpful links and try to find the specific statements regarding your questions. Also try to reword your inquiries if you end up with a list of lemons.
Secondly, spend a bit of time in your local library, it is a much underused and very valuable resource and I have no doubt there are more than a few free ideas out there that have been covered.
This link came up fourth or fifth I think >
http://www.vintageprojects.com/power-tools/pipe-bandsaw.html
And various projects involving homebuilt things also link back to this site (its pretty cool btw).
As well there are sites like this here one which seems like a fairly decent forum for just such questions as yours>
http://www.machinebuilders.net/forum/forum_posts.asp?TID=1412&PN=4
I am by no means trying to steer you away from AS by any stretch of the imagination, its just that many of the questions such as yours are answered elsewhere many times over if you take the time to go look-see.
Thirdly, and for me lastly on this topic, use your imagination, go study some existing ones, figure out what you need to accomplish your goals, two wheels for your band to run on with decent bearings (seen a couple of setups using rubber tired trailer tires etc.), a table to mount your machine on, pullys, a power source, an engine or motor, the gear to adjust your setup, etc etc., ya want ta run it on rails? Then go to the local junk yards and see what is there, don't let the lack of a plan stand in the way of a perfectly good idea
My halve cut 0.02$ fer a very tired Friday evening (sorry if I sound grumpy, I'm not really, just beat ta death today, been a long week), if I come up with better links I will post them as I am sort of curious about this also but no energy to go hunting right now
..................
Serge