Birgit, no offense, but shouldn't the installing company that sold you this system be answering your questions? Your questions seem to be pretty basic ones that should have been covered in a typical hour or so of end-user training.
I'm not implying that we aren't willing to help, but your company obviously paid someone to sell and install this system. I find it hard to believe that training wasn't included as part of the deal.
Thanks for the encouragement, EV607797. However, I will continue to bother this website with questions that may be basic to some of the more experienced participants here. I appreciate your answer, nfcphoneman.