For the upcoming MM tournaments, are they all considered
Marquee events?
And if so, does this mean that retired sets are out for the
next nine weeks?

My understanding is that the first week is a sealed event and the next weeks, the new "Floor" events, are considered types of constructed events.

So yes, retired sets are excluded.

I'll confirm what mohenjo said.

Almost right. The schedule is like this:
All these events are considered to be Marquees, so house rules (including those that affect retirement) are not allowed. However, it's not just Sealed and Floor - for week 4 of both stages, you can build whatever Restricted team you want.

Make sure to check with your venue. Organized play, like politics, is ultimately local.

Maybe I'm confusing what "restricted" means. I thought that meant no retired sets. Is that correct?

That is correct.
It's not the same as Sealed though, and the Floor tournaments has the additonal "50% of team from M&M" restriction, that's why I felt it was worth pointing out.