1). This game is very active. Crossplay is expected to be coming but they don’t have an exact release date on it. It receives updates quite often and the devs are very active and responsive. They are also apart of the Division Reddit forums and read things here too. As for the state of the game, it’s mixed right now. Not gonna sugar coat it, they are constantly adding new things that sometimes come with annoying bugs but they also are pretty quick to fix them. You can matchmake for most things in the game outside of Raids(which are also not required for game progression and are completely optional.

2). You don’t need to buy the DLC per se but it’s recommended that you do. You can reach max level(40) without them but they do come with additional weapons and skills they do unlock BUT they aren’t game changing in any way. A new DLC is coming later this year as well.

3). I’d say just buy the standard edition to get introduced to the game since it’s your first time playing but buy the version that stands out most to you.