In the old days, a young man was required to save up for his family's future support before he was allowed to marry. Today, it is voluntary.
Varies by state. In many states, insurance goes to whoever is named as beneficiary on the documents, without passing through probate. Ditto for IRAs. Taxable accounts and homes are decided by the probate judge following state law. Trusts are nice if the recipient is not good at managing money. A responsible trustee can be named to give them a monthly income, pay bills, or whatever.
This all varies by state though. A local lawyer would be needed to advise you on what works best to protect your family in your state.