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.

Maybe Shessar's North Alarius map in Sue's spectrum overland can provide some ideas.

Grids are just entities, you can use change properties on them and make them as wide as you like (They're usually on a frozen layer, so thaw it before attempting to manipulate the grid). Other things that also usually work very nicely is to add a small glow effect to the grid.

The default line in CC3+ is a line that is as thin as possible (which usually translates to a single pixel). This works fine on screen, but can lead to nearly invisible lines on prints/exports.

You might also simply not be increasing it enough. Keep in mind that when exporting to an image, you take a very high-detailed setup in CC3+ and tell it to squeeze it in to a limited number of pixels. This means something sometimes have to give and give up some of their pixels to other elements in the map. An line can feel plenty thick in CC3+ itself, but when competing with the rest of the map for those precious pixels, it may still be too thin for export.

No. That is only required when adding additional resources to the program. But this is a map bundle, and you can keep your map files wherever you want.

Note that the bundle do contain maps in many different styles, not all of which you will have access to with just the basic program, so you will see red X's when opening these .fcw files in CC3+, but that isn't an installation issue, just that it was made with resources you don't have. For these maps, the bundle still contains the pre-rendered export as high resolution image files so that you will be able to use them all.

When you save a custom pal, it saves a file called fcw32.pal in your CC3+ data directory. If this file is present, ALL maps that doesn't have an attached palette will use this instead of the default palette. So the solution is to delete or rename this file, and CC3+ will revert to using the default again.

Map is now in the atlas. Thanks for the contribution @Ebeneadeser

If you insert an fcw file into another using Draw -> Insert File, the line styles (along with fill styles and symbol definitions) will be copied over. Basically same trick as for copying over missing fill styles.

The maps are now in the atlas. Thanks for the contribution @Wyvern

Actually, as long as it is for non-commercial use, the license allows you to have it installed on up to three computers at once. (Computers belonging to your household, you can't go and share a license with two friends)