Interesting, thank you for the info! Can you clarify what you mean by cycling things through and 30% buffer? Yes I do typically plug everything in in the span of a few mins when getting ready for the next shoot. You're saying basically give like a 30% headroom for wattage so it doesn't draw more wattage temporarily than it's rated for?

Pretty much yeah. When I was doing it I was also using the setup for storage, so I would have a few charging while others were at full. For your set up give yourself some headroom to be safe.

So if I'm reading this correctly, if the overall amperage is a bit short, it's not as much of an issue than if the wattage isn't enough? So in other words if all of them draw 14 amps and it's rated for 12 amps it simply wont draw it, whereas if they try to draw 70 watts or draw that much as a spike and it's rated for 60w that could be? Sorry if I'm misunderstanding.

Wattage is the traditional way to express max capacity, so I was explaining how to get that. As long as you stay in all USB wattage will always equal current*5, so it really doesn't matter which one you use. As long as you stay consistent.

Is there a relatively cheap way to measure this type of stuff? Something like a Kill o watt or even using my multimeter? Not only for safety but I'm also curious how all this works and would like to be able to see it in action

You need what is called an ammeter. Your multimeter might have a mode that measures current, but they usually require putting it in line with the power cable. If you get a separate ammeter, you can get a type that just requires running the cable through a loop (Like this). Or you can get ones specifically for USB (Like this)