Here are a couple of further thoughts for @Frankb (or, of course, anyone else!) in case they might help.
It is really more about ergonomics (especially if one moves away from the quaint traditional keyboard layout—but that is a somewhat separate issue… and skilled typists are qualified to disagree!) and what is convenient for any one user.
Also, the aim is not to memorise lots of shortcut keys (hotkeys), for any of us. If it is necessary to keep using a visual aid to locate shortcut keys, then it is worth considering that maybe those shortcut keys are not the best way of accessing the required function of an application. Shortcut keys are best suited to frequently used functions; other methods (which are much discussed throughout this forum, of course) may otherwise be more efficient.
Yes, that probably applies especially to home row mods, because your fingers are already on the keys, which makes things much easier. The basic idea is great, but it doesn't work for me. OK, let's take a look at it.
When these keys are pressed and held, they press a modifier, for example, which allows you to do various things.
However, this means that the letters A, S, D, F, etc. are typed when the keys are released.
So if I type A and then S in quick succession, nothing unexpected will happen. Both letters are typed when the keys are released.
But if I do the same with A and then N, NA will be typed (instead of AN).
One letter (N) is typed when the key is pressed, the other (A) when it is released.
You could solve this by typing more slowly. Or by having all letters typed when the keys are released, but that slows down typing in a way that doesn't work for me.
You don’t know that for sure, because you haven’t tried it; nevertheless, it is likely that it wouldn’t meet with your approval, because it is quite fiddly to get the right combination of typing habits and parameters, and of course, it takes practice!
No, when they are tapped.
No, it’s a matter not of speed but of cadence, as it is often called in this context, in other words, keeping a steady rhythm (with a bit of syncopation when there’s a capital letter? ), which is important when typing anyway. It is also a matter, as I mentioned, of practice and setting up parameters which are explained well in the article. Oh, and one’s choice of key switches will certainly be relevant!
Anyhow, I am not trying to sell you or anyone on “home row mods”. Many people find this approach hard to nail, and I think I have been quite lucky (and perseverant) to end up with being delighted with this method!
Yes, pretty much, except you don’t need to hold the key until you expire. After a moment, even if you have not pressed another key while holding a key as a modifier, a timeout will occur. The length of that moment can be adjusted.
The concept of tapping versus holding is essentially no different to the way that KM uses it, and Karabiner Elements too. Just remember that the closer you get “to the metal”, the more feasible some of the more tricks become, and even then, it can be fiddly!
The best thing would be for us to sit down together in front of a Mac and you could show me everything. Let me know if you ever move to my area, and I'll invite you over for coffee and cake.
Or I'll just take this. At least it's portable. And it has nice little lights too.
Alas, no-one would be able show you everything… but you don’t need to know everything, especially not at first (much like with Keyboard Maestro). This is a large area to explore, and decisions depend upon personal taste and research into what sounds interesting.
That said, I did previously suggest (a couple of times, I think!) a range of reasonably priced QMK-programmable keyboards which maintain a conventional layout. If you are seriously interested about exploring this stuff, one of those would allow you to experiment and get benefits without you being immediately out of your depth. Otherwise, you can of course look to the Web for more information (documentation, videos, discussion groups) whenever you wish!
Oh, we are back to looking down at our keyboards, are we? Fine, fine…
), which is important when typing anyway. It is also a matter, as I mentioned, of practice and setting up parameters which are explained well in the article. Oh, and one’s choice of key switches will certainly be relevant!
After a moment, even if you have not pressed another key while holding a key as a modifier, a timeout will occur. The length of that moment 
