The idea is that you will look through an eyepiece at a very dim star for an longer than 30 minutes and make corrections using the telescope's control paddle. This process takes a LOT of practice to do well. Finding a guide star 2. I would reccomend using relatively fast film. Faster films tend to be a bit grainy- although they do reduce exposure times.
Exposure times depend on the speed of the film.
Unfortunately, everyone's camera is slightly different and there is no universal method of focussing for different cameras. Focus using the diffraction pattern of a star caused by the grooves in screens of some camera viewfinders. Focus by taking readings from the digital readout of the JMI focuser. I have had some luck in running the focus in and out while taking the average of the results and calling it focussed. However, this method relies entirely on how consistent I am.