Effects from oral absorption generally start appearing within the first 45 minutes.
Caffeine half-life is highly variable from person to person but is usually withing 2-7 hours.
Ephedrine half-life is aroud 4-6 hours.
Some people are more sensitive to stimulants then others.
Considering that most of the effects from E/C stacks are due mostly to anorectic effects and not increased lipolysis, higher doses are not significantly more efficient at weight loss but do increase side-effects.
In your case, there is laregely no need to take such a high dose.
Over the last seven years, I have tried a lot of doses for E/C and found similar weight loss/anorexia with far reduced doses.
12.5 mg E/ 100 mg C early in the morning and again 1 hour befour lunch was well sufficent to cut cravings and allow for effective diet control.
If you were really interested in increased lipolysis, HOT-ROX offers (theoretically) more benefits in that regard.
EC basically just cuts appetite.
Alcohol and ephedrine used togheter can increase feelings of dizziness and lightheadedness usually felt with alcohol. (Together means as long as ephedrine is in the bloodstream, which, with and average half-life of 5 hours means 25 hours following the dose, so technically, its never).
In reality, it has rarely any significant effects, that I ever noted.
As for the dosing, besides the fact that it probably not all that useful to go above 20-30 mg per day, you can dose all you want, the therapeutic index for ephedrine is relatively wide allowing for very large doses to be taken.
Studies on soldiers for increased alertness tested doses up to 400 mg if I remember correctly, so you can relax.
Anyway, you should try Google...