1) I think there's some overlapping in usage. Sometimes a family of several generations is/are buried in the same large plot, and each member's exact spot will be marked by a headstone, while the whole plot will be marked by a much larger and more elaborate edifice.
I believe in Tombstone, Arizona the tombstones on Boot Hill were all pretty simple.
2) There's not much difference these days. Husband can be a noun or a verb. In university, you may major in "Animal Husbandry."
To economize is to watch your pennies. You try to find the least expensive way to have and do the things you need. (The noun is "economy.")
"Husband" as a noun is the significant other of "wife," as in "man and wife," in most cases.
As a verb, it's similar to "economize," but instead of looking out for yourself, you manage some entity (could be a family, or a business, or a property, or some part thereof) in an economical and prudent way.
- A.