As an amateur, I think the main deal is to just eat the costs. It is a crazy expensive hobby, but so is buying state of the art bike gear, this is just a different portal. I go to my local, nobody-ever-heard-of-it bike shop and they have rack after rack of expensive 2-4 grand suspension bikes. Two of those is all the gear you need for setting up a fairly tech shop. You can do it for a lot less, but not with tooling, fixtures, and welding.
Pro, there are basically several ways to go. The best is to find a place to work. This is likely a semi-factory, not going to be easy, but then in wasn't easy when the standard bearers of today went to europe to find info. That said, there are always technical individuals with a special skill in manufacturing or sales, who just breeze through either business development or the technical side.
On the insurance side I think this is overstated. To the exact degree that you need insurance, insurance will not pay off. It is not a social program for the welfare of your cliantele, but a very fragile means of protecting your assets. The best means of protecting assets is not to have them, which is the likely situation many framebuilders will face, or to incorporate etc... as part of the package. Frame building insurance remains available because no large claims have been made or paid out. This is not an industry that can eat multi million dollar pay outs, the insurance remains because claims are not being made. Which is something to consider. One way to minimize claims is to build bikes that will not be ridden, or ridden in dangerous situations. Build trailer queens. I probably wouldn't build commuting bikes, even if there was a market for them.
As far as selling the first frames... I am against selling them to family for several reasons. What role does family actually play? In large part they just like you. One in battening on their good graces, and probably selling them a story that has not really come to pass yet. I think that is bad for family relations. As important, it does little for you. These people can't intelligently evangelize for you in most cases. You can't build a rep by satisfying mom. Of course there are exceptions, if your family is the Von Trapps of Cycling, or something. But in most cases you need to get your stuff out there. The examples I have seen where that became a durable business are for people who had a position in the community, were well known racers, or whatever, and they drew clients like flies to honey. In the two cases I know personally they also owned bike shops.