Hi, reading your OP made me shiver. Please, please, please explain to your family that buying the "young, wild horse" to raise and tame and be their loyal pet forever, is the worst idea ever. It actually might end up from your horse being just a pasture pet, to your horse seriously injuring you or a family member. Raising a colt into being your unique magic unicorn is suitable only for kids tales and experienced trainers.
Look for an older horse, minimum 10 yo (more is better). Look for a horse who was a home-kept horse, a kids horse, known to be gentle and as bombproof as possible. You need a horse who had unexperienced owners and still behaved very well (so, the best would be a beloved family horse that is being sold due to financial reasons)
Most horses, even if they look "perfect" when you see them with their (experienced) owners, learn soon bad habits from new owners who cannot correct them in time. And we're talking about well trained, well behaved horses.
I don't have any advice about the goats; some horses love them, some just ignore them, some hate them. No way to know until you put them together, though a separate pen should be better, at least at the beginning.