Things in life aren’t that difficult to repair, it’s only the first time you do it by yourself it scares the crap out of you. You mentioned you hit the brakes and they went down to the floor to things one when you did the brakes pushed the cylinder or piston back into the caliper but the brake pads on the back bolted everything up went inside the car started it and when you tried the brakes and went straight to the floor. That’s normal because you have to move the pads closer to the rotor next time start the car in park pump the pedal until firmness develops LOL. The second could because by air in the hydraulic system so far I’ve only replaced two calipers in my lifetime the minute you opened the hydraulic system hose line caliper etc. you have to bleed the system to get the air out. And yes it does save money the dealership quoted me 3200 for the front and 2800 for the rear, must be on crack or something. Anyways went on eBay for rotors pads all the way around delivered to the front door for 450 an hour and ½ for actual repair. The only thing you really have to watch out for the neighbourhood is watching you, Oh can you have a look at my car the brakes are given the problems. My answer to that is either you or I get the parts and it’s $100 an hour, I’m at that age where I would like to enjoy the finer things in life.