The OP also asked about a guide for writing slackbuilds.

For me the most useful find in this area was the slackbuilds.org templates page. To the newcomer there are so many esoteric little things to worry about when compiling software in general, but also about "best practice" when it comes to building for a slackware system in particular. These templates not only point out all the things you need to be mindful of, but also how best to deal with them for different compilation paradigms (automake, cmake, python, etc).

Cheers,

Michael

I'd recommend doing a full install, BUT you could always safely leave out the KDE, XFCE, TeX and/or Emacs package groups if you don't need software from those groups.

Omitting those groups will leave you with a relatively minimal system but will still give you a complete development environment, server software and Xorg with a few window managers and some X apps (Firefox, Thunderbird, etc.)

Beyond that, I'd tread carefully unless you really know what you're doing. If that setup still doesn't sound minimal enough for you, maybe Slackware isn't for you. You might want to look at Arch with an LTS kernel in that case.

But Arch has systemd, the opposite of minimalism. ;^)

Haha. Maybe the OP might try FreeBSD then...