L1B expired, I-94 Valid, five years completing soon, possible options

[Raj99]

Scenario:

• I came to US in May 2007 on L1B filed by Company A. In 2009 I went for a vacation to India for a month (30 days) and while re-entering the US I got my I-94 until Dec2012. Since I had valid I-94 Company A could not file for my L1B extension.
  
• In 2011 I tried getting H1B Premium through Company B but it got rejected. Same Company B filed for Labor Certification in Jan 2012 and will be filing for my H1B again in April 2012.
  
• I will be completing 5 years on my L1B visa in May 2012.
  

Questions:

• Can I still stay in US further to May 2012?
  
  • If yes, till when can I stay on H1B? Is it L1B + H1B = 6 years?
    
  • How long does it take to process Labor certification?
    

  [*]If No, what are the possibilities of coming back to US and how?

  [*]I have an admission offer from a renowned University but I'm not sure if coming on F1 will suit my finances.

Request your help and advice please.

[Raj99]

I would appreciate if someone can help me in this regard.