So I've noticd a currency we can't get yet, the Mercury points. My question is, is that a premium currency ONLY buyable with real money ?
Welcome.
AFAIK yes, Mercury points are only obtainable with real money.
If so, what will be exclusively limited to Mercury points ? Skins, or maybe additional characters ?
Skins mainly, but you can unlock characters with it as well if you so desire. Characters are also unlockable with gold, which is the in-game currency you can earn by playing.
Also the mission screen states 2017 season. So far we can assume this means there will be a new season of story every years as long as the game is active. However will these be paid ? (considering the ticket currency my guess would be that, unless missions need to be unlocked later, which would make sense considering it's a story with an order ; a beginning and an end)
Yes, new seasons will be paid.
(I'm not exactly sure if campaigns can be bought separately or not).
However, the ticket system is such, that if you own a campaign and buy a ticket, you can send it to your buddy who owns the game, but doesn't own that particular campaign, and it let's him/her join you on a mission once.
