**Do edit them first**, they assume the dedicated server sits in `~/halflife`. They'll be run in user mode. If you want them to keep running after logging out, *enable lingering* like so: `sudo loginctl enable-linger username`
For a new mod to be recognized by the service files, you simply need to have a sub-directory with a `server.cfg` file and it'll assume you've got a mod directory set up within your installation.