I just made it to 11th level and raised my first skeleton

I know that it follows me as soon as it raises, and I know I can command it via the "order" command, but there are some things that I don't understand.
1. Should I group the skeleton, or just let it follow me?
2. For the undead to cast, must it have been a spellcaster before it died? For instance, if I raise a citizen, it wont be a caster, correct?
3. I did a "help order" and a "help pet", but are there any specific commands that will help me with starting out with undead?
So far the only ones I am using are Order Skeleton report, and Order Skeleton kill mob.
Thanks in advance for any help

Tamoh