Restroom stops?

Yes to both questions. Have a great trip.

Here is a thread on this issue from 2017.
https://community.ricksteves.com/travel-forum/transportation/new-here-do-all-tour-buses-have-bathrooms-on-board

The coaches stops approximately every two hours or less at rest areas. They have to, driver regulations. There usually is a toilet on the bus but in a very tight and/or cramped space for emergencies. Normally, it’s not used because of the frequent stops.

The RS tours knows their audience. It's always about 2 to 2-1/2 hours between bathroom breaks. The restroom on the bus is for emergency only and is highly discouraged by the tour guide for lots of reasons that I won't describe here.

There might be occassions where there is no rest room on the coach.

I had a tour guide that told the group that when traveling by bus a key rule is "go when you can." In other words, always take advantage of every opportunity. There are frequent planned stops on tours.

The Adriatic tour didn’t have an emergency bathroom, but we stopped every two hours.

Our Turkey bus did not have a bathroom but we did stop every two hours at least. On my Ireland tour there was a bathroom for emergency use, but the guide called it "riding the bucking bronco." Best to just go when you can, not when you have to.

Ditto for us on our Best of Turkey tour.

Just returned from trip and no bathroom in Greece or Turkey. Stops every 2 hours and no problems.
Usually there is an emergency toilet but don’t remember it ever being used

Just got back from a 17-day Italy trip, and there were a couple of days when 2-3 people (including me) used the bus bathroom on a days when we left the hotel very soon after breakfast (i.e., coffee). Our guide was of the opinion that if you gotta go, you gotta go. He always let us know when the next rest stop would be, and encouraged us to wait until then, but did not bat an eyelash if we used the bus. It did not get used much, maybe once or twice. But I appreciated not feeling “shamed” if I had to use it.