BF1 has been out for nearly 2 years and (a lot of) people still play BF4. Just because BFV is around the corner does not mean that BF1 will all of a sudden die. Player base is still huge. Personally I'd go for the revolution edition. It's only a fiver more and increases the map count and therefore the player count.
Not sure. I only had a quick go of the single player
Does Origin Access Basic include the BF1 DLC?
For £20 you can get the origin access. Not worth get one game for £8