It looks like only Metal Gear Solid V: The Phantom Pain will have achievements and trophies as the Metal Gear Online portion won’t have any.
The Metal Gear Online Twitter page answered a lot of fan questions about the game. Metal Gear Informer summarized and collected some of the more juicy parts that were revealed.
The biggest revelation is that there will be no achievements or trophies planned for Metal Gear Online. People will just have to earn them via the actual Metal Gear Solid V: The Phantom Pain game.
The maps in Metal Gear Online will be big enough for snipers to be happy about. They also said customization is important to them so we may see some variation in that field.
In terms of gameplay, Metal Gear Online has an auto aim option but players are free to turn it off. The team is also taking measures to prevent cheaters from ruining the experience for others. You can also “opt out” of matches that feature special characters in them.
Lastly, they said it’s too early to talk about DLC or Season Passes for Metal Gear Online. This is something you should address to them closer to the release of the game in September.