Nice collection. It does make testing a bit harder, but at least I have something to try.

I'll see if I can find anything. Maybe there is an overlap with what @Nivenus uses. (Or maybe I am barking up the wrong tree here, but figuring out weird problems can be difficult, so anything can be worth trying)

Hi Hadrian, good to see you.

You shouldn't let atlas maps holding you back. Those are for working on when you have the time and desire (and computer that agree with you) to do so, they're not a requirement. I'd rather see people without maps, than no people at all :)

If you only want smaller symbols, that is quite easy. After starting a new map, just hit :CC2PRESETS: and change the default symbol scale to whatever you want. If you want 5 times smaller, just set it to 0.2.

Note that this just changes the default scale, not the current one, so either save, close and reopen the map as this will open it with the new defaults, or simply click a symbol, and with the symbol on your cursor click in side the map area to bring up the symbol parameters dialog and hit "set normal" and the current setting should be changed to the default.

All tools that place symbols should observe that default setting.

This is a special case that happens with symbols. The thing that happens is that all symbols have their definition on the SYMBOL DEFINITION layer. And if you hide the definition, the symbol disappears. So symbols will always be hidden either if you hide the layer it is on, OR if you hide the SYMBOL DEFINITION layer. So if you are trying to get to an entity by hiding all the other layers, make sure you leave SYMBOL DEFINITION still visible.

As JimP says though, it shouldn't be on the MERGE layer, so use change properties on it to put it somewhere else.

They only affect the current CC3+ session. The default at launch should be smart symbols on, but they won't reset by simply loading a new map.

Note that you can also find the same setting in the symbol parameters dialog (the one you get when right clicking with a symbol on the cursor)

Disabling smart symbols disables everything that is smart about symbols, like connecting symbols, control points, random selections from the catalog, etc. Basically, they lose all behavior and gives the user full control.