Are you going to be keeping this car or just want to get a short, quick fix? That is the question. If you just want to get by for awhile your plan may work. If you plan to keep the car, expect it to be safe and dependable for a long time, it won’t work.
Paying someone to slap new pads on is not a complete brake job for a 12 year old car. And at 74k miles I am assuming that this is the original brake equipment on the car, never been changed.
New or rebuilt brake calipers all around, all 4 if discs or 2 calipers for the front discs and cylinders for the rear drums. Disc brakes have pistons that push the pads against the rotors. When you change the pads you have to push these pistons back into the caliper to accommodate the thickness of the new pads. The pistons are probably pitted or rusted, and when you push them back into the calipers this old, pitted part of the piston goes back into the fluid bearing part and you are going to get a brake fluid leak and failure. There are also slide pins that the 2 halves of the caliper slide on when the pistons move. These often get stuck, they need to be lubed and cleaned. The rubber boots protecting the pistons get cracked and allow dirt and moisture inside. The best solution is new or newly rebuilt calipers.
The cylinders that activate the rear drums are simpler, and fairly cheap, but you want to replace them too. Same issue, they will leak, may fail causing loss of brake pressure and a very bad day.
Then there is the rotors and/or drums. I side with the recommendations not to turn or shave these down. It just makes them thinner and weaker. If they are still within tolerance they can be reused and the pads will adjust to the minor ridges and groves. You are already hearing screeching noises. They probably are not reusable. New ones needed, although it may just be the wear indicator tabs causing the noise. These tabs warn you that you are about to damage the discs but haven’t yet. Attention needed soon.
You probably have 12 year old brake fluid in the system too. Brake fluid does not cycle through the system. The stuff nearest the calipers or cylinders gets dirty and absorbs moisture. Your brake change will bleed most of that old dirty shit out of there when he bleeds the brake lines after install. A better, just as cheap, solution is to change out ALL of the fluid. One guy with a hand held vacuum pump can do this easily. Most shops would do this as a routine I think.
The brake lines also need to be inspected for cracks and wear.
Many of the things I have said are the same thing that you will hear when you take it to the shop for an estimate. And you will think that they are just padding the bill, selling you services that you do not need, etc. No, they are telling you what a full brake job entails. Of course they could still be trying to screw you, but knowledge is power, understand what needs to be done and you will probably find that taking it to a good shop for a full brake job is cheaper and a better investment.