I would not use wire for several reasons, first it's unnatural and can't imagine them feeling as safe and comfortable as a full floor of bedding.
Second, the poo has to be mashed with their feet through the wire to hit the bottom. Mine average nickel sized turds xD
Third, it coats the wire and gets sharp as the other poster mentioned and will start cutting up their feet.
Lastly, to clean it, you would have some scrubbing on your hands as quail poop is like cement when it's dry. Oh and you would also have to clean where the poop lands and since there's no bedding it will smell more because it will take longer to dry.
I like to use newspaper with wood shavings and the quail actually like bathing in the shavings as well, although they still much prefer a sand box - the holy grail of quail

when it's time to clean them, I take the quail to a temp cage with a fresh sand box to keep them busy and simply roll up the newspaper with the dirty shavings on top and put it in a yard bag or you can compost it. Then I use a dustpan to get the rogue shavings and put the fresh newspaper down in the way it can be rolled up next time
I would partition the too large brooder VERY SECURELY so no chicks get past it and die without the heat/water/food. Absolutely no gaps on the edges and make it a few feet high - trust me.
Quail chicks do not last as long as chicken chicks after they hatch without food and water - most people will recommended taking them out when they're mostly dry once a day whereas chicken chicks are commonly left for three days.
They drown easily in water even shallow water so yes marbles or rocks
You have to teach them how to eat and drink, eating is the easy part but drinking may take more time, I sprinkle some crushed dry grass so it floats on the water so when I touch the water it moves around on top of the water which will encourage them to peck it and they will realize their water source
I use bird netting used to protect fruit trees for the top of the brooder as they will be flapping around in no time practicing their new wings and they harmlessly bounce off of it as long as you don't have anything hard in the brooder for them to land on.
I use paper towels for my brooder until they're old enough to not thing wood shavings are food

about a week or so!
Good luck with your baby quail - some tame up very nicely (usually when hatched in smaller groups of about a dozen or so in my experience) and love to be pet and snuggled... I even have some that love to get in my sleeve and hood hehehe.
That's one of my pet group who slipped her face into my wide sleeve and just stayed there straining every so often to get in further
She tidbits for me like a chicken rooster does for a chicken hen when I give them certain treats hehehe