I think this is out of scope for the API. But wanted to check first.
Looking to create an app for users to draft a team on my site. Essentially I'd just need rosters and players. Once the draft is finished, users can import the results to Yahoo. It's my understanding that the API is for Fantasy League specific queries, rather than player/roster list for whole league.
Is this something achievable from this API; or do I need to look elsewhere?
You can get a list of players for the whole league--the only restriction is that you can only get 25 at a time. The returned data will give you information about what team a player is on ("editorial_team_name" or something like that).
However, you cannot import data back to Yahoo! as far as I'm aware. I think the only PUT operations the web service supports is Fantasy roster management and managing transactions (FAAB bids, trades, etc.).