I can answer a few questions. I raise and milk LaManchas and mine give 3-5 quarts of milk. They average about a gallon-plus a day each during the first couple of months lactation and then slowly taper off from there. A good milker will produce milk for 10 months. Some folks have milkers that keep on going after that.
I can't say enough good things about LaManchas
They are heat tolerant and do well under extreme conditions. Mine do well when it gets cold too.
A milker needs forage in the form of browse and good clean hay and 3 lbs of alfalfa pellets or good alfalfa hay. They need alfalfa for the calcium. It is more important than grain. They only need smaller amounts of a grain mix on the milkstand and during the latter months of pregnancy. My milkers get 2 lbs of grain on the milkstand...that is 2 small metal coffee cans of my mix of mainly oats. No sweet molasses feed is fed here.
Loose goat minerals are a necessity, goats become copper deficient without proper minerals.
How much water? Well, less than a cow for sure. I don't know the amount but they like a good long drink after being milked and they need their water checked a couple times a day....sorry, not more help.
A big pasture is nice but a pen is a must for locking up at night because of predators. A goat is lunch for so many animals. Also, they are herd animals and you really need at least 2 or they will be incredibly lonely and miserable.
Goats are kind of deserty animals, they are all over west Texas. So they should do well for you if they have enough cool water and shade....oh, and remember Sanaans get sunburned.
