Is there any real single player mode to this or is it mainly mp focus?
There aren't game modes. There are missions that you can complete in different ways, as you wish:
- To go in a 2-4 people coop team (all friends)
- To go in a 2-4 people coop team (with random people with similar level via matchmaking)
- To go in a 2-4 people coop team (mixture of friends and random people)
- To go alone (more difficult, think Monster Hunter or Destiny)
Players can drop in or drop out in the middle of the mission or when you are in the hub, your ship (or someone else's ship).
I assume communication between players is desired for hard difficulty missions, but at least in the easy and medium difficulties I played the communication isn't needed.
I played mostly alone, then in some missions with random players and only a few with friends.
As you play, you unlock cool stuff like new weapons, super attacks, passive skills, cosmetics etc. Playing alone you still get them, but at a slower pace.
Mission loot and rewards are shared between the players of the mission, and playing with other people you kill more stuff, complete the mission fster and collect more loot, so you get better rewards. And playing with other people is way easier to play missions of harder difficulty.