Your running hot issue is the first thing to tackle, since you know your a/c fans are bad start there.
See if you can spin them by hand, you can stick a ling screwdriver behind the grill and spin them, just becareful not to stick your screwdriver through the condenser.
If they do not turn you can replace just the electric motors, tech section.
The thermostat is located ontop of the engine, follow the upper radiator hose from the radiator back to the engine, that goose neck looking thing is the t-stat housing, 2 bolts and it will come off.
Clean the mating surfaces with light sandpaper or emery cloth, clean with rubbing alcohol and then put your new t-stat and gasket in.
Make a mark on the old t-stat with a marker on the side that faces out so you put the new one back in the correct way.
Start with the t-stat, 15 min job, again the tech section has the gasket part number.
Always start with the free/cheap/easy stuff first.
As these guys said clean your throttle body and make sure the vacuum line from the dizzy to the intake plenum is there.
There is a nipple ontop of the intake plenum and another on the side of the dizzy, replace it with vacuum line if it is missing, you can buy vacuum line at the autoparts store.
Then do your turn up.
Replace the O2's last.

 

Just a few thoughts on smell and overheat with AC on -

1. The inside fan is below the passenger dashboard, mounted with three bolts. Ease it out (they are expensive) and empty out trash. The air intake is under the cowl of the hood, and you will need to fab a filter for this, see the tech sticky section on this forum for a how to for that (will keep out nesting critters, etc.).

2. Speaking of trash, pull out the rubber strip between the water radiator and the air conditioner condenser, look down in that space and clean out any trash. Rover builds it this way to keep out lily pads when you are fording ponds (called "wading" by those on the other side of the pond). If junk blocks air flow, it can impact radiator, and also lower the temp of the air hitting the fan clutch, which will keep the clutch from engaging when it gets really warm. Many clutch units are about 20% coupling at normal temp (so they save gas) , and when clutch face gets to 170 degrees or so they begin to re-couple to a maximum of 70 - 80%.

3. Turn on ignition to "run" position, but don't crank truck. Turn on AC and fan to any position. Both condesner fans should come on, and you should feel air blowing out the back of them toward the engine. My POET (previous owner - exceptional twit) wired replacement fans backwards, air was blowing out the front, and with AC on it would slowly overheat at idle.

4. I replaced my wimpy fan clutch. It was so wimpy that when warmed up it would spin by hand multiple revolutions - most of the internal fluid was gone. This forum has a good write up on a $50 Chevy cross reference fan clutch. Now my fan "roars" at cold startup, and moves enough air to spin the AC fans even though AC is off. In a minute or two that roar goes away and air flow drops, that is normal.

5. Shop around for radiator rod out service - some big shops seem to want to base it on the MSRP of the vehicle. My little 2 man indy shop charged $65 for acid "boil" and rod out, soldered up a couple of extra things as well. Guys that rebuild bulldozer radiators don't have to make their boat payment off the next SUV radiator that comes in....

 

Download the RAVE in my signature. It has 99% of the info you need to repair the Disco.

 

This is very good advice, the same thing goes for suspension and muffler shops.
Any of your chain stores are not going to cut you a deal but the small shops will, especially if you pay cash and do not need a warranty.
And you can haggle with those guys.
Stay away from the large shops, they have large overhead and corporate offices to report to as well as sales margins.
Joe's Crab Shack and Auto Repair just wants to have a repeat customer, he will also let you bring in your own parts.
And cash is pure profit.