If we get married in the US will she be allowed to leave the US until the green card process is completed???

If she qualifies then she can apply for advance parole which would allow her to travel while the green card case is pending.

Re-Entry on Advanced Parole on a pending criminal case.

Your criminal case need to be evaluated by an experienced immigration attorney before you travel outside the USA.

Every case is analyzed in its own merits as to what constitutes an acceptable investment for E-2 purposes. I have found that a sound business plan...

Thanks very much for ur input.

You can file at anytime within the 90 day period before your green card expires if you and your spouse will be filing the I-751 together.

What is a better option to go for, fiancé visa or file an immigration petition after marriage??

In many of these type of cases I recommend clients to file the I-130 marriage petition and if in the USA file the adjustment application.

Can I apply for the K1 visa before I fulfill the 2y rule? Due the fact it takes a while for them to approve it.

You cannot apply for a K-1 until you have met the 2 year foreign home residency. You can enter the US with a B or other visa but the time spent...

Do I qualify for an artist visa or a green card?

We would need to review your case in detail before opining on the questions you raise.

L1B to H1B transfer

No you cannot transfer to H-1B as the H-1B is not valid.

Do I need to have some minimum number of days left on my visa for my wife to get her H4?

No minimum number of days is required but note that her H-4 will be valid until 7/24/2016 unless you get na extension.

Changing from B2 to F1 status

You can file Form I-539 for a B extension and then file another I-539 to change your status to F-1.