I have, by default, an slocate script in cron.daily, however I see no evidence that that script ever runs. Is there something I need to do to make Slack run that script daily, other than have it in that directory and make sure it's executable?

check the time stamp for /var/lib/slocate/slocate.db. it should be updated daily.
and /var/log/cron should reflect an entry for cron jobs that were ran. you should see something like this for cron.dailyl:

Dec 9 04:02:00 mnlssa CROND[17880]: (root) CMD (run-parts /etc/cron.daily)

The timestamp of slocate.db as stated above. On Slackware cron does not log anything. You could email the result of every cronjob by adding your emailadres to the entry in crontab.

Slackware doesn't include anacron (like some other distributions do), so if you power down your machine for the night, make sure that your cronjobs are set to run when the machine is actually switched on.

Well, I did some reading on crontab (man crontab) and found the -l switch. As root

showed a nicely laid out schedule for hourly, daily, weekly, and monthly tasks. As user, no such schedule showed up. After googling on 'crontab howto', I found this page:

which explains the various entries I saw when I did 'crontab -l' as root. An easier explanation than that found when doing a 'man crontab'. After using 'crontab -e' as user, I was able to create the proper cron file for my own account.

I also noted earlier, after looking for various cron files with

that KDE has a kcron I could have used, but after loading that app I quickly noticed that I would never learn a thing about crontab that way, so ditched it early.

Thanks.

note as well that the crontabs are stored in /var/spool/cron/crontabs

Yes. I found that out when loading the file via 'crontab -e'.