Is there any danger in bonding the DC- output to Ground with a short wire, to ensure my circuit ground is also referencing the home ground? I'm not sure simply letting the outputs float is wise,
Assuming the power supply is properly built either is fine.
Side-note: I have an after-market laptop supply that's two-prong... it works either way, but if I plug it in one way the metal trim on the laptop has an interesting "buzz" to the touch. Not shocking, but definitely noticeable. I suspect that when it's plugged in the right way the output ground is weakly referencing neutral, and the "buzzy" way has the output ground weakly referencing line voltage (it's floating - it'd be quite a bit more than buzzy otherwise). The OEM supply with the 3-prong plug? Fully grounded to the shield of the DC power cord.
Power supplies without an earth connection often have problems like this, especially as they get larger.
Capacitors have to be placed between input and output to control EMI. In an unearthed design this ends up with the output being "weakly referenced" to the input. How weak that reference is (or to put it another way how big the "touch current" is) depends on the size of the capacitors. Unfortunately there is a tricky compromise here, bigger caps are better at suppressing EMI but produce larger "touch currents". Larger power supplies tend to suffer worse from this than smaller ones (this is why laptop PSUs from reputable brands are usually earthed while phone chargers are usually not).
In an earthed design this can be mitigated either by tying the output to ground (pretty much universal in in desktop PC power supplies, occasionally seen in laptop supplies) or by splitting the EMI suppression capacitors into two parts, one from output to earth and one from input to earth.
To what do I connect the grounding-setup, as a whole? (The mat, or the wrist-strap, or whatever.) I've been told everything from a water-pipe (would have to run a wire to the ceiling, there's nothing down low in the room), to the center-screw of a wall-outlet (really!?) … and, practically-speaking, how do you suggest I do so? Wrap a bare/stripped copper wire around the screw, or around the pipe? Or what?
You want everything Earthed. The center screw of a wall outlet is probably easiest. Make sure you verify that your work area's electrical installation is up to code, and there isn't a ground neutral reversal, for example. Your mat and wrist strap will probably have spade lugs for making the connection.
I know I should be working on an ESD-disappating mat, with an ESD-disappating wrist-strap on at all times. To what do I connect these? Do I connect them together, i.e. to a common point, as well? (From my still-fledging understanding, there should be a single shared ground amongst all points in the circuit, which I suppose includes your body if you touch a conductive part of the board, so …)
Connect them both together, back at Earth.
Is the “ground”, as discussed in terms of dissipating triboelectric
potential / electrostatic charge, the same as the “ground” in circuits
I'm working on? i.e. should I be connecting “ground” in any circuit,
with a wire, to the same grounding-system we're discussing here? Or is
that a separate ground? I've also got a bench power-supply with a
‘ground’ banana-socket, which I'm sure will be used for circuits, so I
suppose … if the answer here is yes, I should wire that to this
common-ground as well?
This is a topic for a separate question all together. Ground has come to be a generic term for circuit common, or zero Volt reference. You may, or may not, be able to make Earth your circuit common, depending on your circuit in question. If your bench power supply is galvanically isolated, it's typically ok to make that connection. More often than not that is through the ground clip on an oscilloscope. For ESD purposes, you don't connect to your circuit. You need to be careful about this, and research it further.
The bench multimeter I've acquired has a grounding screw on the back, next to the three-prong power-plug. Should that grounding-screw also be wired to the common-ground discussed here, i.e. the same as my wrist-strap? (Also, why the hell is there two grounds on that, then; one as a screw, and one as the third prong in the power-cable?)
You can, but for your purposes, it probably won't help much. The safety ground for the chassis is part of the three prong cable. That lug is intended to be connected to a low impedance instrumentation ground. Such a ground will be at approximately the same potential as earth and likely on its own ground rod, but won't won't have all the noise of the building's main electrical safety ground. The safety and instrumentation grounds must be tied together at some point, by code. That is typically as close to the ground rods as possible.
Best Answer
You are missing the point here. If you are unfamiliar with how things work regarding protecting static sensitive devices you should use an ESD mat that is usually connected to ground via a discharge resistor (usually around 100 kΩ to 1 MΩ).
The point here is that when you place sensitive parts on the mat they remain at an ESD potential close to ground. And when you sit down to do work with those parts you firstly discharge yourself to the same potential as the mat by touching the mat and/or remaining in contact with the mat via a wrist-strap and curly wire. You are then at liberty to touch and handle the components in the full knowledge that in doing so, you won't cause an ESD event to damage them.
But, even before placing the components on the mat you have to be aware about handling. In other words, the sensitive components must be in an antistatic bag so that when you pick them up (with or without the wrist-strap), you won't cause them damage.
You then place them on the mat and only open up those parts from the packaging once you are connected to the mat and are absolutely ready to use them. The target circuit board should also be at "mat" potential so that when you place the components on the circuit board you don't create another possible ESD event.
In other words, it doesn't matter what potential the mat is really at because everything you do is relative to the mat potential. However, ground is a nice convenient point to connect the mat to.
When you grasp what is happening, you can learn how to handle components without a mat or wrist-strap but, until you grasp that, do the basics first and then learn how to handle stuff without mats and wrist-straps.
Testing whether your lamp is earthed or not is largely irrelevant if you don't understand the basics and don't follow correct procedures. If you don't want to use a mat or wrist-strap, you better get to grips with how you handle components without them i.e. once you open the protective component package, you never release those components; you keep 'em in your sweaty palm/fingers and anything that you want to apply them to (like a PCB) you grasp with your spare hand to equalize potentials via your body.