Retiring Lead Wolf and Naming Heir Questions

I have been super paranoid about this since I accidentally murdered my lead's mate, I have been browsing the forums but can't quite get a straight answer.

I am planning on replacing my lead with her daughter, but have some questions

1. When making a new lead, does the wolf keep their level like I have heard?

2. Can the new lead be any age or is there a limit? Too old/too young a no go?

3. Does the wolf have to be unbred?

Any clarifications would be greatly appreciated :)

1. yes, wolves will keep their current level (and consequently any stats gained)

2. I can at least answer that too young isn't of a concern; wolves under a year old will be automatically aged up to 1 year of age (if they are under a year of age) upon selecting them as your lead.
too old however I can not answer!

Thank you!