I do mostly agree with JulianDracos and Kertis Henderson here. 1TB drive/16GB ram is fine, and as Julian says, a fast processor is better than a slow one with many cores, although a certain amount of cores is highly useful (I recommend 6 or more, but most CPU's will fulfill that today)

As for the screen, I fully agree with Kertis, don't get a 4K one. I used to have one on my old Work laptop, and it was a pain for most things. I prefer to go a bit higher than a full HD (1080p) screen though, I find a 1440p one much better. But there are two factors here, first of all, your eyesight, 1440p naturally makes things smaller (and buying a 1440p just to increase the scale factor in Windows is a waste), so make sure you're comfortable with the size, otherwise do go for that 1080p one. And of course, a higher resolution screen do mean CC3+ is a bit harder to run, so it should only go along with a somewhat good CPU, if you go budget on the CPU then do not get a 1440p screen.

My own laptop is a Lenovo Legion Pro 5 (1TB/16GB/i7-13000hx/RTX3070/2560x1600), a machine I find well suited to most task and pretty good value for money.

The only way is really to just load them up in the house style editor [HOUSEOPT] and look at them one by one.

To quickly look through them without clicking yourself to death, take advantage of the fact that Windows GUI components are keyboard friendly. Simply use the top dropdown and click on the very first style in the list to select it and collapse the list, then as long as you don't click any other controls, it will be the active control, and you can go through the styles using the arrow keys.

The best option is to keep the template lines in a clean file.

If you copy them over to another (temporary) map, you can just go wild in that one, deleting all the fill styles. You'd have to do it manually, but at least you don't need to consider which to keep and which to delete, just do them all. Then you can copy the lines from this clean file afterwards.

(You may want to save that temporary map every now and then, mass deleting fill styles sometimes causes CC3+ to crash)

There is a tutorial on page 94 of the User Manual.

For the map size, it is simply a case of multiplying the number of hexes with their size. Just keep in mind that hexes are wider when measuring corner to corner than edge to edge, so you need to know what those 24 miles of yours actually represent.

Have you remembered to add the Wall Shadow, Point Light Finalize effect? Lighting doesn't start working until this effect have been added.