1) Stop it. Never say that or think that again. I don't care who told you that or how you think you have proven it. Give it up.
2) Stop it. Keep up. Be consistent.
3) Stop it. Resist the urge. Lern the material and craming will be a waste of time. Cramming also tends to contribute to lack of sleep.
4) Stop it. You are CAUSING the frustration. Why would you do that?
How many hours? That is just not a useful question. Solve the other problems first.