1) dose it twice daily. Ephedrine has a half life of 6-8 hours so I would say earliest your second dose should be is 6 hours after your first and latest would be 8 hours after your first dose.
2) 8 weeks and then time off. Stims for too long is never a good thing
3) you will need to taper doses.
Week 1-2: 25mg e
3-4 32-37mg
5-6 48mg
7-8 60mg
As far as caffeine I would say 100mg with each dose is enough