The new ongoing series is coming out in March or April, after Blackest Night: The Flash wraps up.
Zolomon was de-powered during Final Crisis: Rogues' Revenge. Thawne has been dead. His resurrection hasn't been explained yet, but will probably figure into Blackest Night.
Barry's resurrection has been pretty much "It happened." There's a vague explanation in Flash: Rebirth #4, but that's it.
Barry was trapped in the Speed force I guess for years. Along with Johnny Quick, and Max Mecury. Basically they wanted Barry Back, and snuck max, and johnny in through the backdoor too. Zoom did take credit for trapping Barry in the speed force in Flash Rebirth 2 or 3 I think. Even though it seems a little ridculus at this point. EVen though these issues have been worth reading for the incredible artwork, the stories leave me with more questions than answers. Like if Flash was running from the Black Racer for however long he was gone, they've been careful not to say. Then how did he just kinda escape?