Thanks Dave.
I used to develop these types of coatings and then installed them as a side business for several years. What the guys above said is all good info. Stay away from the HD/Lowes sold stuff. Even the 2 part coatings they sell dont last. The material isnt that horrible, but they want you put it on way to thin. When I did garages and commercial floors, we usually did ~15 mils of color coat and another 5-7 mils of topcoat. The 2K rustoleum kit would be about 5-7 mils, and no top coat.
I would recommend a good quality epoxy for your base coat and top coat with a Aliphatic urethane or polyaspartic clear, if you want high gloss and the gloss to last. Your target thickness for the base coat should be 10-15 mils DFT.
You will need to rent a concrete grinder, like the Edco above. Some of the bigger HD have them, or other rental places. Dont forget the grinder heads. Some places rent those separate. When Ive had to rent machines they were about 75-150/day and the heads were extra. If its just a sealer, expect to get 150-300 sq ft/hr from a single head grinder. If you can rent a double head it will go quicker. Use a 4-5 gal shop vac for dust control. Just be prepared to stop every hour or so and tap the dust out of it, and probably trash it when your done. Grind until you see the surface porosity of the concrete. It will probably go from a darker grey to a much lighter gray. Once you grind an area, broom it off and dribble a few drops of water there. If the water instantly soaks into the concrete your good. If it puddles or sits on the surface, you'll need to grind more.
Once the grinding is done, broom up all the dust (could be 20-30Lbs or more....) then go over the surface with the shop vac. Get as much dust up as possible. Also if you want a really good job at some point you need to grind the edges. The edco grinder will leave a strip around the edge about 2-3" wide. I used HF angle grinders with cheap diamond blades for a long time. Get on your knees and just scuff that all up. Doesnt have to be perfect. Keep the grinder flat to prevent gouging. If you have any cracks or seems to fill now is the time. Use a good 2K joint filler. Get some backer rod or sand if needed so you dont have to use so much joint fill.
You can get wide rollers at HD/lowes and those make the job much nicer, use 24" wide. Tap off any areas, poles, doors etc. MIx eopxy based on instructions. BE aware some formulas require you mix and leave it in a mass for 10-20-30 min to start the reaction. Mix a smaller amount first and using a brush cut in about 2-3-4" around the back of the hanger. Mix some more and then pour a line a few inches away from the area you cut in. Usually something 2-3-4" wide is good. If the epoxy is thin and spreads really well you can pour more of it out. If not pour less. The idea is to then spread that out to the desired thickness. Cross roll, so first roll N-S then walk thru if you have spike shoes or leave a spot thats clear so you can roll E-W. Then just repeat these steps until the floor is coated. Spike shoes make it easier to cross roll and fix an heavy or light spots. While you are rolling the color coat is the time to broadcast any chips or sand grit.
Once the color has cured, usually overnight for epoxy, do the same for any clear. Some people use shark grip or other stuff in the clear for grip.
Its not really that hard, but using a good material at 10-15 mils and doing a good job on the grind is key. As a ball park, i was based around atlanta and did jobs over the SE. A garage with chips and clear was about $4/sq ft. Plain color was 3-3.50/sq ft. That was material and install. Material should cast you about $1-1.50/sq ft. You can get some good epoxy at Sherwin williams and PPG porter stores. A couple near me carried 2K epoxy and could order other formulas if needed.
You cna see videos on you tube of people doing installs. Let me know if you have any specific questions.