Armored cable is no better electrically. If you are building/re-building I don't know if it's cheaper that regular conduit (if want or need the physical protection). Your electrician can advise you.
But heavier gauge (a lower gauge-number) will result in less voltage drop. Not really an issue... but the voltage drop in a cable is related to the resistance (length & gauge) and current. With higher current you get more drop. Or if you've got two more circuits with their own wiring, each set of wires has less current so less voltage drop.
There are electrical codes for amperage & distance but I assume you can go heavier gauge.
I believe the only thing special about hospital outlets is there is a spec for how hard they are to un-plug. So plugs don't get accidently pulled-out as easily. (Your electrician can tell you that too.) They MIGHT not hold any tighter than another outlet, but there's a spec-requirement. But if I trip-over a cord, it's probably better that it comes-out that I fall down!
One will be dedicated to big, high current power amp.
It might be better to separate the audio from everything else. That gives you SOME noise isolation in case something else is putting noise on the power lines. (It doesn't make a big difference since everything is connected together back at the breaker box.)
What's the actual amperage rating on the amplifiers? (It's usually labeled on the back near the power connection.) As you may know, class D amplifiers are nearly 100% efficient (at high power) so they don't suck much more energy out of the wall than is going to the speakers. Class-A amplifiers waste a stupid amount of energy, even when idle.
And if you don't know this... There is a "power transformation" so you can pump more
current into the speakers than comes-out of the wall (at lower than wall-voltage).