It will probably contain helpful hints that will speed up your design process. Magic runs on Sparc 5, Ultra 5 and 10. Magic currently isn't supported on any architecture but the Sparc. Try using a Sun workstation instead. If we get Magic running on the others, we will announce it to the class.
Magic hides the actual contact layers underneath the contact abstraction.
As long as the layers the contact goes betwen are touching the contact layer, it is a short circuit. If you do happen to overlap them, it doesn't matter. There are two sets of contact rules in the Scalable CMOS handout. When I run ext2sim I get a spice netlist that has numbers as node names. My layout labels do not propagate.