Every night about 1% of the items you have are lost, as nothing lasts forever. This applies to treats, feed, materials, tack and intermediary items. So if you have 1000 apples and you are not producing anything, you will lose around 10 apples every night, during the game reset.
The horses have realized that now that water has reached AVH, they might as well drink it. A thirsty horse will not be able to enter shows or breed, and will lose happiness each night. They require as much water as they require food (depending on their level)
Employers can hire other players for a rebuilding job. You can set the number of buildings to be rebuilt (on the ranch) and the employee will just have to click the rebuild button and wait for the building queue. Please take the building time into consideration when you set the job time.