I've worked on my own cars for 25 years, so here is my opinion (what I would do if it were my car).
First off: SAFETY FIRST. I've known many people killed when a vehicle they were working on fell/rolled on them so always make sure you're aware which wheel of your vehicle is attached to the drivetrain and which is the "free rolling wheel". So that you don't put the wrong wheel up on a ramp and have it move on you. And try to put the car on as level of a surface as possible. Putting the parking brake on and wheel chocks is good practice (even parking another car close to the end of the direction the car "might" move (overkill but you never know). Also make sure you're putting the stands under something that will support the weight and not damage something (don't put it under a suspension component for example).
Tribute: Needs struts/shocks? Is it riding weird, bouncy? Are the tires showing signs of bad suspension (cupping, irregular wear)? Replacement recommendation of suspension based on mileage is kind of dumb, oil, fluids etc YES. But suspension wear can vary greatly depending on how/where you drive so if it drives fine I would let that go. I don't know what kind of suspension your Tribute has but ball joint/control arm wear would be a greater concern to me since if that breaks your wheel will change directions quickly and can cause you to wreck. Does the car shake, etc? 126k miles isn't really a huge amount of miles for a car with a lot of highway miles but city miles yes. If the car is not exhibiting any adverse driving characteristics and not wearing the tires oddly I would just keep driving it and not worry about it until those things happen. But do put the car on stands and move the wheel around and check the "play" in the suspension links and bushings just for reference.
Coolant flush can be tricky if you don't know the proper way to bleed out the air for your particular vehicle (which I'm sure you can find online somewhere), but measuring how much coolant you drain (compare this to the fill spec but keep in mind that you won't always drain out what the "capacity" is because a lot gets left in various parts of the engine) and make sure the same amount that you removed goes back in can help ease your mind when doing a job like this (to make sure you aren't low on coolant). Normally you turn the heat on full blast to open up the channels, just look for the proper procedure for your specific vehicle online-I'm sure there is a Mazda/Ford board (I think the Tribute is the same as is it the Explorer or Escape? can't exactly remember, but some Mazdas are rebadged Fords so procedures should be the same)-what I'm saying is since there are more of the Ford models sold than the Mazda equivalent so if you find the same Ford procedure on a Ford forum you can probably just use that.
Ford: I once had a 92 Ford Taurus that I changed the radiator on. It was an automatic so you'll need to unhook the fluid lines that run through the radiator (just make sure you replace any lost fluid). The radiator change wasn't that hard if I recall correctly. Thermostats are pretty straightforward usually, just make sure you put it in there the correct direction (there is usually some kind of index on the part so it will only go in one way but just make sure to compare it to the orientation of the current part).
Oil pan gasket, hmmm I'm pretty sure if it's front wheel drive this means dropping the cross member or raising the engine to get the oil pan off to replace the gasket. Look under there to be sure (I can't recall exactly). Probably an expensive job if you can't just easily remove the whole pan without moving other things out of the way. How much oil? Depending on how much someone wants for this, I might just get under there and clean the area real good with brake clean or similar to get as much oil off the area that is leaking and seal it up with some kind of caulk or just something to slow it down (JB weld might work-I've tapped an oil pan for a turbo drain line and sealed it with JB Weld with no leaks). Or cardboard under the car. But I'm cheap like that.
Heater core, if it's not leaking I wouldn't worry about it.
CHECK ENGINE LIGHT. YOU CAN GO BROKE TRYING TO CHASE THIS DOWN. My Taurus CEL came on from about 25,000 miles to 225,000 Miles, yes a Ford Taurus that actually lasted that long. My philosophy on CEL: Check all the fluids, monitor the MPG you're getting. If you have to go through inspection get a cheap scan tool to reset the thing. I've had CELs come on and off on multiple vehicles I've had and reset them and it passed. CELs are a PITA. Good luck.
Of course, get quotes for all of this stuff and see what you think is worth doing.