- I just don't know if I should be saving my map in a separate folder, or if I should use the "mods" folder inside the SOMA directory (the editors keep opening the main directory, so I dunno).
Strictly speaking, you can save your mod files anywhere you like. However, the general rule of thumb is, yes, to save your mod files within a "mods" folder inside the SOMA directory, further separated inside a folder specific to the mod you are working on. For example, if you are working on a mod called "DarkPlace", then your files should be saved within the folder "<your SOMA directory>/mods/DarkPlace". (One reason for doing this is because the mod launcher automatically checks the "mods" folder for runnable mods.)
From there, convention would state that you should separate your mod files the same way that SOMA does, i.e. with a "maps" folder, a "config" folder, a "script" folder, an "entities" folder, etc.
- When the tutorials talk about editing config files, I don't know if I should be editing the main files, or copying them somewhere to be edited separately, or what.
There are two modes of modding. First is when you're actively developing, tinkering, or concepting mod ideas. Second is when you're preparing a mod for release.
When actively developing, it's convenient to edit SOMA's config files themselves. This is because, when you run SOMA in developer mode (i.e. with the "SomaDev.bat" file), it loads the SOMA config files, not the config files of your mod. Because of this, if your mod is dependent on your config files, if, for example, you are working with custom entities, modules, or lang entries, you generally have to add these changes to the SOMA configs in order for them to appear in SOMA's developer mode.
When you're packaging your mod for release, however, then your mod needs to have its own versions of the changes you made (for reasons that I hope are obvious). Because of this, if you only make your changes to SOMA's files, it can be difficult to track down everything that you did and copy it to your own mod folder. Therefore, the recommendation is that everytime you make a change to the SOMA files, you make the same change to a version of the file that you copied to your mod's folder.
- If I'm playtesting a map, does it mean I can't play the main game without unediting the config files again?
It depends on if you made changes to SOMA's files and what they were. If all you did was add new maps, maybe some custom entities, then it probably wouldn't affect the main game at all. If you customized scripts or made a module with a persistent effect, however, then yes, your changes will be reflected in SOMA itself. To prevent this, one handy practice is, whenever you find yourself about to edit a SOMA core file, make a backup of that file. That way you can switch between the original file and your modded version without losing either one.
- Do I have to manually build a directory structure to mirror that of the main game for the mod to work?
Strictly speaking, the only thing your mod needs to work is a "resources.cfg" file and an "entry.hpc" file, and both should be in your mod's root folder. From there, nothing else is absolutely mandatory in terms of naming scheme or folder structure. That being said, it will be easier for you to understand the layout of the files and how they work together if you stick to SOMA's convention, at least until you understand how it all comes together.
- What's CodeLite for? Why can't I just use Notepad++ to do scripting, for instance?
You can absolutely do scripting in Notepad++, or any raw text editor you choose. The reason CodeLite is convenient is that it is an IDE, which offers perks like autocompletion and Intellisense. It's become a bit of a hassle to work in where HPL3 is concerned, though, so personally I recommend using VS Code (a sort of middle ground between a text editor and a full IDE) and following the
guide on the wiki on how to get it set up for Angelscript and HPL3.