How to Convert B1 to L1 and is it possible L1 to GC?

[Harun Al Rashied Tanvir]

Dear Sir,

Status: Now i m in B1/B2 status, i m planning will be convert B1 to L1 with businees, i have telecom company in Bangladesh, i m a director and last year, i visited to USA, that time i opened one company in NY, now i'll go to USA with family then apply L1 visa
My query:

1. after apply how many time need get L1 visa?
2. After get L1 visa when i'll apply for green card?
3. how many employee maintain in USA company for getting Green Card?
4. m i eligible to fill up my file without immigration laywer?

thanks,

harun