Re: How do you keep a game from becoming a chore?
It's one thing to let players come up with NPCs (which is a great idea, as it's an easy way to get your background cast of characters put together and make sure that they're characters that the players like/find useful/will interacct with). But unless you're ready to basically turn the game into a freeform and/or make all the players GMs, you need to take control of those NPCs once the players have put them on the board.
I'm in a game where the GM is only minimally involved in steering player-created NPCs. In some cases, it's not too bad...the players use those NPCs for RP purposes and otherwise just kind of let them remain in the background. In other cases...the NPCs become, basically, echoes of that player's PC, so whatever that player wants to have happen, regardless of whether or not it fits well with the GM's vision of the game, ends up happening...it becomes a significant burden for the GM to try and keep up with, because those players like to keep haring off on their own storyline (because there are enough characters, with all 'their' NPCs, to make it a plausible attempt, in-game). So the GM has to devote time and energy to supporting their private little plotlines, on top of trying to keep the rest of the game moving. I don't resent the creation of the NPCs, as I've created a few myself...but the fact that those NPCs are being used as a lever to demand special focus from the GM annoys me (and I've brought that annoyance up with the GM on a few occasions.) I can't imagine how being a GM would NOT feel like a chore, at that point (but I don't enjoy the whole GM aspect of gaming, particularly, so it easily feels like a chore to me.)
But it seems to me that, if your players are throwing so much information at you that it becomes laborious, it's your prerogative, as GM, to say, "You're welcome to create any NPC that you like...but I control them." I also happen to think it's your prerogative to say, "You can only have (X) NPCs, so choose them carefully." I know not everyone agrees with my take on it, but in my book, it's YOUR game, as GM, and if I'm going to play in it, there's an implicit agreement on my part to play the game within the guidelines you establish.
But it's also incumbent upon you, as GM, to make those guidelines clear to your players, and to enforce them when and if they get challenged.