Getting to the Water Pump meant removing a cooling manifold containing the thermostat.  There's two things going on here:

• Thermostat
  This component works by blocking the flow of coolant out of the engine until the fluid reaches a certain temperature, making it easier for the engine to run when just started.  Even in a "hot" climate, the engine will start "cold", relative to its operating temperature.  Check out this article for an excellent, in-depth explanation.

• Manifold
  This distributes the coolant to different parts of the engine.  There's seven (count 'em) different places coolant flows from this manifold, with the water pump providing the necessary pressure to push the fluid where it needs to go.

Doing the Replacement

Manifold just removed

Replacing the thermostat was imperative because when this component fails, the failure causes the liquid flow being blocked independent of the temperature, resulting in in the engine overheating, leading to all kinds of problems, the most common of which is an engine block that forms cracks because of the combination of heat and pressure. Since this part is sub $10 and it's being removed anyway, changing it is the right thing to head-off any (expensive) failures down the road.

Using an 8mm socket, I removed the three bolts around the housing and extracted

Can't re-assemble incorrectly!

the old thermostat and O-ring with my fingers.  In went the new O-ring ($0.39, so I splurged!) and thermostat and back together went the manifold.  This is where I noticed a very neat design element: the manifold halves are polarized so they can't be assembled incorrectly.  I can't imagine this costing any more to manufacture and the design costs would be virtually nil, even if saves just .05% of the parts from mis-assembly, FordMoCo is ahead of the game. Clever!

The $0.39 seal; a nail maybe?

The picture of the new and old thermostats wasn't very good (camera problems!!) so I've included a picture from the top where the deposits from years of use can be seen. Otherwise, there wasn't much visual difference between the two.  The old part looked a bit worse for wear, but it spent the last 10 years submerged in a chemical bath, alternating from sub-zero to scalding, so that's to be expected.

Left old, right new and shiny

As mentioned, replacing this part isn't 100% necessary, as the existing part was working correctly.  For the low cost and since the system was already drained of fluid, and I had to remove the manifold anyway, it just seemed like the right thing to do, considering the cost caused by failure.  Failure of this cheap, easily accessible part can bring down the entire engine -- the classic "for want of a nail, the kingdom was lost" effect.  You see it so often, in others as well as ourselves, wondering how such a common, well known human failing continuing, seemingly, unabated.  How many times have we cast aside something small, ignoring the beckoning in the back of our minds, yet still be surprised at the final outcome?

Yet letting go of the little things is paramount to living a sane life -- concentrate on all of them and madness will ensue.  One can never know the loss of which nails result in the loss of the kingdom and one can never keep track of them all, or even figure out the relative importance so to fix the kingdom-dissolving nails.  Keeping a kingdom seems to be a combination of vigilance, hoping to fend-off enough small problems before they become large (or combine to be large), and sheer luck.  For now, we'll do our best by our Freestyle and hope for luck.

New seal installed

There's one more seal on the manifold, where it attaches to the water pump.  I replaced this as well, at the cost of a little over $4. Why so much, did I get an artisan, free-range seal? Hopefully these components will last the life of the car.  I didn't put anything on the seal in terms of lubricant, I don't usually unless I get specific instructions otherwise, as this film could interfere with the mating surfaces.

Once the manifold was back in place, all seven of the hoses were re-attached.  The hoses appeared to all be in good condition, no need to replace them now.

Re-filling the System

This was the last part of the water leak issue.  The car now needs to be filled with coolant, which was drained at the start of the process. The best advice is to use an air lift tool to remove the air from the system and then use the vacuum it creates to pull in the new coolant. Being without a air lift, my approach will be to fill the system from the overflow tank, run the engine and keep an eye on the fluid level, since air rises above water, the system will slowly purge itself of air.  Not being sure of how much water remains in the system, I'm going to fill with straight coolant first and then remainder with water and guess it will be approximately the correct proportion (should be 50/50 water/coolant).

This worked well enough.  I let the engine run until it was at operating

Coolant overflow tank.  Use a funnel!

temperature, when the thermostat opened,  it sucked most of the fluid out of the overflow tank and I saw some bubbles burp forth and then another draw on the reservoir of water in the tank.  A few more burp/draw/fill cycles and the fluid level reached steady state.  I added about 2/3 a gallon of water, so I should be at approximately a 50/50 mix given the coolant system wasn't completely empty when refilling started.

Ford uses "standard" ethyl glycol for it's coolant/antifreeze.  The compounds in the coolant have less heat capacity than water.  Since coolant is sold in a concentrated form, using 100% coolant in a system would result in the engine running hotter, because the coolant can't absorb as much heat as water.  Not enough coolant will not lower the freezing point of the water enough, so in cold areas, the liquid in the block could freeze, blocking coolant and since water expands when frozen, potentially cracking some of the engine components.

And not just any water.  Peel out the sub-$1 per gallon for distilled water.  The water delivered to your tap, if supplied by a municipal system, contains a mix of chemicals to keep your teeth from rotting, make the water palatable and prevent beasties from inhabiting the water lines, none of which an engine requires.  Water drawn from a well contains an even larger set of minerals and chemicals.  Using distilled water is one of those "nails" that's easily accommodated.

 All Done with Water Pump 

This was the last chore for water pump replacement, the most pressing problem

Installed pump, no leaks

in the engine bay and I think the cause for the car's sale.  I've included a picture if the shiny new water pump installed with the cooling manifold back in its rightful place with all of the hoses reattached.  The car's been running for a week with no oil stains, so if the seal is leaking, it's not in enough volume to drip down the engine bay... yet.  As for the water pump itself, no leaking either.

Disposal, not just for oil

Don't just pour whatever came out of the engine down the drain or on the ground!  This thinking goes for coolant too; treat this waste like used oil and dispose of it properly.  Most auto parts stores won't take used coolant, so this will require a little more effort on your part, but we all live here, so do the right thing.  Used oil reclamation generates a small profit, since coolant would only cost money for disposal, there's no "free" recycling offered at most parts stores.  If you don't have curb-side pick-up for hazardous materials, take it to the nearest collection center (search for "hazardous household waste collection near me") and fork over the few bucks for proper handling.  

I poured out the remaining distilled water (this is 100% clean, I would drink it but pure water tastes not so good) and used the jug and the container from the new coolant to transport my used coolant to the disposal center, so these can be recycled as well.