I have two mini goats - a pygmy and an nigi cross. Mine have horns, so they are not with the horses at all (those horns are belly level on the minis)...I have a really friendly one and the other one (which is a rescue) is scared to death of people, not aggressive, but scared.
Mine are both wethers (gelded male)...I would definately not start out with a buck...they can be aggressive and they stink to high heaven.
Mine do not eat pasture grass, they eat weeds and leaves/tree branches...I always say they eat more like a deer would than a horse, so their pasture is primarily woods. They do eat a mixed hay and goat feed (not a grain, it is a pellet with a little corn in it)...they also have salt block available to them, loose supplement and baking soda (for bloating)...
They are really cool and alot of fun - I'm getting a couple more next spring. The do need wormed regularly, but not quite as often as a horse, ivermectin. Some people use paste wormer on them, but my vet said no, it has to be very accurate, so I get the shots from my vet and administer them myself (overdose can kill a goat)- about 3 times a year. They do need their feet trimmed every couple months, but this is very simple to do, the vet can show you how, you use prunning shears to do this.
I love my goatees, if you want more info, feel free to PM me...I could go on and on...