Really like the idea of night and day being incorporated, especially with the dock. To be honest though, I think you would be better of without the lever. i.e set amounts of zombies per round, but there is a set amount of time between the end of a round and the start of the next, but this could decrease depending on how well you did in the round. eg there could be a set time of two minutes (just say, could be something different), but every down in the previous round reduces this time by, let's say, 10 seconds.
With the monks and the button promt - don't do button prompt, they just don't fit in well with fast-paced games. Perhaps have some other way of dealing with them (not sure, but will have a think).
Otherwise, pretty good ideas - personally, I've always wanted a sort of streety map where you actually have to hunt for perks and box etc.