It looks like your flange is okay on the inside. It looks like that is the pipe where you see pieces missing. But that could be from when the pipe was cut in the original installation. Sometimes we get real rough edges. The spanner flange should give you another five or even ten years. Hard to tell.
I'm not sure about the bowl wax you ordered. If it's just the 4" wax instead of the wax we use that fits 3 and four inch waste lines then I don't see any advantage. But you might as well use it.