Based on your pictures, I think 3 "kits" (6 gallons total) (each "kit" is a gallon of the color, and a gallon of hardener= 2 gals/1 KIT) will cover it. You might be able to spread 2 kits to work, but when you run out of product and the floor isn't covered, you're fucked. If you're gonna use the Sherwin product I do, call your local store and make sure they stock it. Most don't, and it'll take them a day to get it in.
Your roughest areas aren't terrible, and neither are your smoothest. I'd say the product will stick to both, but I would go the extra mile and run a concrete floor grinder over the whole thing to level everything nice. I rent these by the day for $70-$100.
After that, use the hose or a powerwasher (better) to blast all the dust off the concrete. I sqweegy (sp?) the excess water off to help it dry quicker, but you may not need to be in that much of a rush. either way, make sure it's dry.
After it's dry, you have your product, and the flakes (if you're going to use them)....I buy more H&C Deco flakes (from Sherwin) than I know I'm going to use, because again, shit sucks balls if you run out and your product is drying/mixed. I like to use larger amounts of flake than what you would see on the "Johnny Homeowner" kits, cause more flakes looks kinda like granite. Anyhow, for a standard 2 car garage I'll usually order 14 bottles:
So, I found one of the 24 oz. bottles I use for referrence. For yours I'd buy 17 bottles. You'll return many of them, but you won't run out after you decide how heavy or light you want your flakes.
When laying the basecoat (part A & B of Tile Clad), you mix both parts 1 kit at a time, wait 10 minutes, and start rolling. If you're working with no walls still, you won't need a brush to do corners, but remember the roller you use for the basecoat will be trash when you finish. Don't even waste time trying to clean it.
Get a good 6' x 6' of product rolled out, and then throw your flakes as heavy as you wish. The key I've found to even dispersion (is that a word?) is to put the flakes in a larger bucket than they come in (pictured above), grab a handful, and the throw is all wrist (as gay as it sounds). Handful of flakes, wrist flick to the target. You'll figure it out after a couple throws.
6x6 sections, in a swift pace, you'll find what works for you, tape a line under the garage door seals, and walk when you're done.
For the rexthane clear the next day, you'll want to sweep the loose chips that didn't stick first. Or, as I like to do, blow loose chips out with a leaf blower. The clear is a simple roll ever sq inch, no biggie. It's like rolling water on, but say 3 gallons of that on yours for a thick clear.
That's it. To make things go a tad faster when we're working with time sensitive shit (the base coat), I like to use an 18" roller, as seen by painter Chris here: