You will also need to supplement milk with a concentrate feed, but if you are rearing calves, the goat kids will do very well on calf mix (18% protein). I don't feed ad lib, except hay.
Yes hay rather than silage - much safer for youngstock in particular.
You need to have a reliable supplier of male kids (and decide if you can rear them horned, otherwise your profit is gone) and also a reliable sale outlet.
The meat is fantastic, esp slow-cooked. We eat ours as (slow) roasts (legs), cubed (for curries and stews) and minced (for whatever you need mince for...)