If we are part of a Multiverse is it likely that every universe is the same age ?
We have absolutely no idea. To the best of our knowledge, we have only a single universe. If evidence ever surfaces that we live in a multiverse we'll know more.
Since there is zero evidence that we are part of a multiverse, you can supply any answer you like.
Also, since other universes, even should they exist, are causally removed from ours there would be no way to test any answer, so again, you can supply any answer you like and no one can prove you wrong.
Depends on the version of multiverse. In eternal inflation new universes are formed continuously, so they come in a variety of ages: some brand spanking new and others literally older than dirt. I can't think of any version where they would all be the same age. It's a bit of a trick question - like what color is a pink fairy?
In general, no. Multiverse models usually include events which birth "pocket universes" multiple times.
Separate names with a comma.