Don't waste your time/money on an expungement ... it won't work for immigration purposes.
You should meet with an attorney to discuss your convictions 48 months of probation indicates a very serious DUI conviction.
If you are low income go here: www.justice.gov/eoir/probono/states.htm or http://www.immigrationlawhelp.org/
1. apply to a school & get admitted
2. ask the school's foreign student adviser how to apply.
No, student isn't easier than tourist. A tourist only needs to show enough money to come and visit for a few months. A student needs to show $20,000+++ to cover their expenses for at-least the first year.
Why are you contacting us before you contact the school?
As for the H ... talk to the lawyer that did the papers ... you probably need an H visa stamp and need to wait until September 20 before you enter the US.
Contact the court in the area where you got the first divorce ... it is absolutely required.
I know that it isn't easy to get divorce decrees from Africa ... but, it can be done, I get several each year.
As for getting divorced again, that might work.
Meet with a lawyer ... I sense that you're currently in the US and that, perhaps, you don't have a current and valid visa/I-94 ... this adds extra problems to the 'mix'.