Convert from L-1b to L-1a or not?

I have worked past 2.5 years on a L-1b, and assume I have 2.5 years left for a total 5 years of duration allowed for L-1b. I am from a country other than India or China (for priority date purpose), and plan to go for a GC in a year given employer agrees. My current responsibilities are inclined more towards a L-1b than L-1a but that might change in 6 months to a year as I expect to get into a managerial role. Looks like L-1a has advantage over L-1b given a longer duration of 7 years, and a shorter/quicker process of GC thru EB1. My questions:

a) Should I change my L-1b to L-1a for these advantages? Any disadvantage or lack of advantage? What requirements are there to apply and get approved for the change? Costs to my employer?

b) Can I apply for EB1 after the switch? If yes, is it easier to get GC thru EB1 rather than EB2?

c) Can I self-petition for EB1 as multinational manager once on L-1a?

Thanks a ton!

Yes you may convert to L1A but make sure you have the right documentation. L1A is for multinational manager means you should have been a manager in more than one country(usually your home country and USA). If you are successfull in getting L1A, applying for green card in EB1 is lot more advantage than EB2. There is no Labor for EB1. You will get your green card in approximately in 3-6months.EB2 usually takes more time than EB1 but depending on which country you are from matters a lot. For China and India, the wait time is like 5-10years. However, the only downside is if you apply on EB1 and get rejected then you have to leave the country sooner than later.