As in the title.

I believe it applies to the Bosmer who live in Valenwood. Outside of Valenwood, that depends on how religious said Bosmer is.

http://www.uesp.net/wiki/Lore:Green_Pact

Just because. Here's a list of potions/poisons that Bosmer can make if they're strictly following the Green Pact:

http://theskyrimblog.ning.com/profiles/blogs/green-pact-alchemy

^^^

It depends now, they allowed violations of the Green Pact in TESO Lore. They didn't like it, but accepted it. http://www.uesp.net/wiki/Lore:The_Green_Pact_and_the_Dominion

I assume they follow it, but they allow certain degrees. Though it only applies in Valenwood as mentioned above.

My bosmer Morrigan is a strong follower of the green pact. But the fact that she is in Skyrim has allowed her certain liberties. She will use things such as wood but only dead wood. You won't find her cutting down a living tree. She lives in a log cabin. Built by someone else of course. Her bow is made of wood, so are her arrows other then the tips and feathers. She dabbles in a lot of alchemy which involves a lot of plants. But she only takes just what she needs. She makes the cannibals over in Markarth look like a bunch of pansies though. She won't think twice about eating the flesh of man vs the flesh of animals.

Its a fun RP really.