F1-OPT, sponsoring parents for B2 Visa

[YSIVAM]

Hi,

I am on F1 - OPT and I am going to sponsor my parents' trip to the USA. I have submitted all my paychecks/tax returns and an Employment Verification Letter that states that the company will be filing for an H1-B in March/April 2013. I have few questions;

1. Would there be any problem in getting the Visa approved since I am on F1-Visa?
2. As per DS-160, I am the person that is going to sponsor the trip. Does this have any negative impact on the visa approval? Would it be better if my parents do a self-sponsor (they have the documents ready for it)?
3. Is the lease agreement (for the address in the USA) a mandatory document that needs to be produced?

My F1-OPT expires on August 31, 2013 and the duration of stay for my parents has been mentioned as '90 days' in the DS-160 and my parents' VISA interview is on the first week of Feb, 2013 which means my parents will be returning back before my OPT expires (I hope I will get an approval for H1-B by that time). Does this have any disadvantage?

Please give me some suggestions/opinions regarding the above mentioned issues. Thanks for your valuable time.

[immihelp]

1. That's fine.
2. If they are able to show that they can financially take care of their own trip expenses, that is always the best. Otherwise, they need to show that you are willing to pay for their trip.
3. You need to provide some proof of your address. Utility bill, driver's license etc.