Which is the better way to renew it, by mail or by efile?
-Either is OK, up to you.
If by e-file, do I need to attach a copy of green card, driver license or pass port?
-You may be requested to upload the required documents online. The website will give you instructions.
I am currently working, do I need to get some authorization for work?
-Do nothing if you still work for the same employer. If you change job before you get the new card, you may just go to the local USCIS Office to get the green card stamp on your passport by bringing the I-90 filing receipt.
Thank You!