In /usr/share/doc/manual, you have two SuSE guides: the administrators and users guides.
1) from the main menu, Control Panel - YaST2 modules will get you to various services.
2) ctrl+alt+del in suse same as in windows. rarely needed. use ctrl+alt+backspace instead (restarts the X server instead of rebooting).
3) see 1) above.
4) don't know what would be the *best* for suse, but suse comes with its own firewall application. go to main menu Control Panel - YaST2 modules - Software - Install and remove. click Administrator Mode and provide root password. from the search dropdown list box, select Package Groups. look through the lists for firewall and antivirus apps in the software which in on installation media.