Newbie in need for help plz! :)

[Irithori]

This seems like a good starting point for suse
https://www.suse.com/de-de/documentation/sles11/

[Being]

Guys, thanks a million!

What a great community

[Irithori]

system resources, connections, logged in users, disk space, backup mysql databases, cron jobs etc.

system resources:
top, on newer systems atop

connections:

man netstat

e.g. netstat -tunlp, netstat -anp

logged in users

man w

diskspace

man du
man df

backup mysql databases

man mysqldump

There is a bit more about this topic.

cronjobs

man 5 crontab

Additionally, as a midterm goal:
Once you know enough to manually setup your apache, mysql, ntp, dns, etc
it might be good to invest time to automate the setups.
puppet or chef are very powerful tools, that enable sysadmins (or more precisely DevOps) to maintain thousands of machines.

Eight machines can still be handled by one guy manually.
But if they would be automated, you have much more headroom for new stuff and also recreating a service on a new machine is then just a matter of minutes.