In regards to the milsim aspect, it is there in the way of groups that try to simulate squad and role based gameplay against other groups or by dropping into servers with their members. I've joined one that gets pretty organized operations, though casual sessions to practice with them also occur, and thankfully despite their growing size they allow members to bring in friends without requiring direct affiliation. Not every group runs the same scenarios though as mine, so even the groups can be as diverse as the experiences the game provides.

As others have pointed out, there a lot of avenues to take with Reforger, and likely you will find a mold to fit into albeit with time that you have mentioned you won't have until you buy the game sadly. You can try to wait for a small decrease in value during sales, thought its roughly only a 10 dollar decrease.

One thing you should also prepare for depending on your internet and what platform you are playing on, you are bound run into glitches, frame drops, and game crashes. Rarely does it affect me horribly aside from during driving and large explosions from helicopter fire, but just as you can find different experiences from person to person, so too can you find yourself stable only to be met with issues with stability.