L1A, L1B or EB1 to GC?

Hi

I am an Indian national currently working in UK. I work as a manager for an oil company and am looking to move to the US. I have doen a bit of reading on various visa categories but am unclear on a few things. I have worked a manager from Jan 2010-Jan 2012 (in Saudi Arabia) then moved to UK worked on a staff role till May 2013 and have since worked as a manager again. I know L1B would be a straight forward option but reckon that it will take longer for a GC.

I have a few questions

If I apply for a L1A and come to US, how quickly can i get a GC. Can my company apply for EB1 instead of going through the hassle of L1A? is EB1 equivalent to a GC or will it take more time to get a GC after EB1? If I end up getting a L1B for ease of process what is the quickest way to get a GC?

Apologies for multiple questions, but want to make sure that I get it right before i start talking with my company.

Thanks

Raj