INI and HAL files

/home/cnc/linuxcnc/configs/
Notice cnc is the user name so it will be whatever user name you have on that PC.
And it does not matter at all where the config files are, as long as they are readable and have no spaces in the name (this was an issue way way before, no idea if still true).
You can have configuration files on a USB stick or network share or ... and still they can be run and used to control the machine.
For editing the config files, never ever use windows or office suits, use only simple text editors like xed or gedit or geany or nano or vim.
Use the PncConf wizard, it can do pretty much everything needed, and it can also edit the created configs.
Another thing, you can have multiple configs for the same machine with different setups, so make as much as you like till you get things working as you like them to.

Yes, all those things will need manual HAL edits.
You don;'t have to put everything in the same file, the [HAL] section of the INI can pull in as many .hal files as you need. It may make sense to have the toolchanger in a separate file, for example.

You can also have several INI files in the same config folder, sharing HAL files, tool table, etc. This can be handy if, for example, you have a part-time rotary axis, or an alternative geaometry. (for example my mill has a horizontal spindle that I sometimes use, and that means swapping the Z and Y axes.)

I might be worth skim-reading the list of available HAL components to get a feel for what is available. You are likely to need the "carousel" component, for example.
linuxcnc.org/docs/stable/html/
Scroll down to (and expand if necessary):
Commands and userspace components
Realtime components and kernel modules