A Day / night cycle is nice (don't really miss it if absent), but I have found NPC schedules can be a bit of a pain if you want to talk to a particular NPC and it is the middle of the night. Presumably the guards would not let us camp in front of a shop, for example, so you'd have run around killing time or go find an inn or farmer's field to sleep.

How much money do you think it should take to add NPC schedules and extra dialog, weather, weather effects for the environment, extra dialog for the weather, changes to the skills based on the cycle of the moon, balancing, etc?

IMO this is the stretch goal with the most amount of work for the least benefit. It would be nice to have, but I wouldn't cry too much if Larian only got 800,000 (missing the henchmen stretch goal would be a little disappointing).