You can't cos a goat is not a horse!
You can use a goat to raise an orphan foal, at least partially. However, the goat may not produce enough milk as the foal grows and there is a difference in the amount of fat in the milk of goat and horse. Also, it gets tough for the foal to nurse from the tiny goat as it grows. You may prefer to milk out the goat and feed the foal by hand. I would suggest that you feed at least partially with a mare's milk supplement available from your feed store to make sure the foal gets the proper nutrition. Leave the goat in with the foal. Goats make lovely companions for horses and your foal needs a companion as much as milk.
A goat
I have never heard of a nurse mare foal. If a mare dies, leaving a newborn foal, some mares are very maternal and they will let another mare's foal nurse. If there is not a lactating mare available, a nanny goat is a good substitute.
Amnocentisis or an ouiji board
If she comes into estrus again.
What you have to do is find the castle then the Queen will ask you if you've lost a foal. The foal that she found isn't your but on one of the hills you can see your foal eating a bunch of flowers. I can't tell you where the hill is. You will have to figure that out for yourself
You can't.
In order;cub, kid, cygnet, gosling, foal, lamb.
The exact color of the foal will vary according to the exact genetic coding of both parents and without that information it can be almost impossible to tell you what color a foal may be.
On the side of your horse's page, close to the bottom, it says "Your mare is __ months into gestation. She is in foal to____________(stallion's name)." == ==
No, because the external features of the foal are complete at that point. However, if you've been observant, the vet might be able to gather enough information to let you know when the foal might be due.
An orphan foal.