MicroVax and OpenVMS for dummies

I finally got some terminals (VT525) and DEC MMJ cables for my MicroVAX 3100/85. I tuned it on expecting it to be dead and found a copy of OpenVMS V7.1 is installed on the MicroVAX (well after I tried both serial ports on the terminal and the screen came up at 9600 baud). I have never owned anything DEC or any computers that didn't have built in video, sound, keyboards so I have a few questions. What kind of reading material do I need to understand how these systems and software work? Is there a default login/password for OpenVMS V7.1 Is OpenVMS available for download? Is V 7.1 optimal for this old unit (I think it has the full 128MB but have to check, dual 2GB? drives and built in CDROM). I assume I can use some old PC or Mac software to login over the coax ethernet (does it do DHCP?) once I get some ethernet cables and I know what the heck I am doing. What kind of server was a MicroVAX 3100/85 anyway (files, applications, etc)? What are optimal setting for the VT525 to work with the MicroVAX (serial settings, color, lines, etc). Figured I would try some completely different systems last year and ended up finding the MicroVAX before it was turned into razorblades. Took me a while to get the other parts needed. TZ