L1B visa apply green card?

Hello,

I am new to US and holding a L1B visa. I think the company I work for is big enough to sponsor employees for their green card application (a few thousands employees in the US). Before I talk to my boss and HR, I would like to have opinions for the following questions?

1. Is it too difficult to apply a green card using L1B?
2. Should I ask the company to apply a H1 vias for me, then apply for green card?
3. When can I start (after a year of valid L1B)?

I really appreciate if you can help,

Thank you in advance,