There's many ways to do this,
for checking if the computers are on, you could use ping to see if the machine responds:
ping -c1 ipadress
or if you want it more convenient, make a script and add all of of them.
Since you said you are new to linux, i am assuming you don't know how to make a bash script.
Just make a new text file (say you call it check-if-up.sh), with the following content:
#!/bin/bash
# machine 1
ping -c1 ipadress &> /dev/null && echo "machine 1 is up" || echo "machine 1 is down"
# machine 2
ping -c1 ipadress &> /dev/null && echo "machine 2 is up" || echo "machine 2 is down"
# ..
The command there will ping the ip, and echo one of the 2 answers depending if up or down. You need to give it permissions to run with
chmod +x check-if-up.sh
then you can run it with
./check-if-up.sh
It should output something like
machine 1 is up
machine 2 is down
...
For shutting down the system the shutdown command itself supports a time already.
To shutdown at a specific time (using 24h time)
sudo shutdown -h 8:15
or after a certain amnount of time (say, in 10 minutes)
sudo shutdown -h +10
You could also add this command to the crontab to be repeated every day, in case it never changes. I believe there are also graphical shutdown timer apps in the software center, so if you prefer that try a search there.