Filing form 2555 for several years

Hello,

I am living abroad and want to file my tax return for 2014, 2015 and 2016.

Question 1: Should I fill both form 1040 and 2555 for each year?

Question 2: I fill form 2555 for several years at the same time, should I check 6a or 6b on them?

Thanks for helping out!