So is the City inaccessible for the rest of the game?

 

Side quests didn't show failed but i can't enter the city anymore, will all the quest Npc's survive the riots?

 

Do i have to load or can i play on and do them later on?

Seconded. 

Yeah, i have defiance bay inaccessible as well, then got new bounties, one of the bounties is in the catacombs, which are now unaccessible. That means i'm unable to get new bounties before doing the catacomb one :|

Once you reach Twin Elms, Defiance Bay will be reopened. I'm not sure about the status of some specific quests, but certain areas such as the Brackenbury Santiarium will be closed off after the riots. Most of the NPCs in the city resume their normal activities though.