A better approach would be to seek admission into the university of your choice, get an I-20 from them and go for the F1 visa stamping in your home country. This is the best approach for studying in the US on a student visa.
Now, if for some reason you do not want to go to the consulate for a visa stamp, then here are the answers to your questions.
1. Better to not disclose, because a B1 is not meant for studies.
2. AFAIK, there is no time requirement. But if you have read a 45 day limit somewhere, no harm in waiting for 45 days.
3. Like I said, it is better to get a F1 stamped from your home country.
4. Till the duration of your study.
5. Depends on a lot of factors. Your documentation, finances, ability to convince your intention to return, the school you are seeking admission etc.