First, some basics about my work experience: Been Equity almost 10 years (in June!), worked on at least 8 different contracts off the top of my head, from the very low-end, to the very top. And I mostly work as an ASM. I think this is a salient point because, truth be told, despite the fact that I sign a contract with a producing entity, I'm getting my day-to-day instruction from the PSM, not the GM or producer.
You ask / raise a lot of points, so I'll just write about one for now: Breaks during rehearsals
I rarely have a full meal break. Only on my most recent contract, where the company voted for a 1.5 lunch break, did I actually feel like I could take a longer break for myself (and, truthfully, I voted for the 1 hr. break). In a standard 1 hr. rehearsal meal-break scenario, I count myself lucky if I have 15-20 minutes to eat my lunch (I always bring my own food). On this most recent show, I took a leisurely 45 minute break. Now I'll admit, I was first trained under very intense SMs, working in stock environment with "no time to lose." Since then, I've worked on bigger and more high-profile shows, where, inevitably time is short and pressure is high, so I do the same thing. But even when the room doesn't require a huge changeover, I feel compelled to use some of that meal break for other show-related tasks: prepping a report, phone calls / emails I can't take during rehearsal, even run-of-the-mill paperwork. The truth is, all of these tasks need to be done at some point during the day, and the shows I work on rarely afford me time to remove myself from the room to do them. My choice is get a little done now, and it's less I have to do on the time that is truly mine in the evening.
But this isn't just a question of my personal habits: there is an industry standard expectation that, when the cast/creative return from a break (whether it's a 5, a 10, or a meal break), the room will be prepped and ready for the Next Thing, whether it's a new scene, or a full run-through. I have rarely received any instruction from my PSM (no less a Producer or GM) instructing me that I should or should not work through a break, because it is, I think, an assumption about our role in the process. We think ahead, we prep ahead. And no matter how big your team is (even if it's full of interns and non-Eqs who's rights we aren't currently discussing), it's the Equity SMs who are ultimately responsible for the room, and the room's readiness for that Next Thing.
To the point I suspect you are driving at: I don't think any Equity contract (that I've read) protects or addresses the SM team's right to breaks during rehearsals. But I'll be honest, I'm not sure Equity can, because it IS a bigger industry standard they'd be up against. If I told a director the room wasn't reset because "I needed to take MY 10," I can envision several scenarios: one where the director throws a fit, another where I am not hired for the director's next show because I'm not a "team player."
Though this is a question posed in the performance scenario, I could take it a step further: You ask if any contract / instruction has been given telling an SM to arrive prior to 1/2 hour...I'll speak here to the rehearsal version of this question: No one instructs us to arrive early for rehearsal either, but what if we didn't? Coffee wasn't made (the horror!), new script copies still to be copied, collated and distributed, and props not set? The truth is the SM work day is never equivalent to the actors'. And in the rehearsal world, I have easily done 11 hours of work, in the rehearsal hall alone, before heading home. One of the reasons I hate when directors chose to use the Straight 6? Because, with an hour book-ended to the beginning and end of rehearsal, guess who actually works a full 8 hours without an break? The SM team. It's my least-liked rehearsal option for this very reason. Now that I phrase it that way, it sounds like it easily violates standard labor law (isn't an employee required to have a break after 5, 5.5 or 6 hrs. of work, depending on the state?)