Possibly. 4A has hinted to it. But there are no promises or anything. If something comes out, it will be in a long while. I'm guessing 2016 earliest. And if so, it won't be continuing Artyom's story, 'cause his story is done.
There probably will be. Glukhovsky seems quite keen to make as much money off the franchise as he can. Let's just hope that the series dies before it gets stale, uninspired and unambitious.
Nope. I wasn't referring to Deep Silver at all. Glukhovsky doesn't work for Deep Silver - he's the author of the first two books from the franchise.
A quick google brought up multiple old articles saying that they planned on doing next-gen ports. The quote was also from April last year, and also confirmed plans on multiplayer and an SDK, both of which are looking like we might not get a chance to see.