For overview of signature campaigns, see here:
https://bitcointalk.org/index.php?topic=615953.0I doubt you'd be able to get anything as a Junior Member, and if you're very busy then this whole thing is really not for you. Campaigns require posting a lot or doing something for the advertiser.
(Also, it's not about getting paid in ETH, it's mostly BTC).
That's not correct, there are many campaigns open to Junior members. And the time needed for translations is FAR bigger than the one needed for a signature campaign. I'd suggest to go for campaign which don't ask for too many posts every week, if you are very busy.