Commodore 128 cabling

Hi. I picked up a C=128 with a pair of 1571 drives and a 1902 monitor at a thrift shop the other day. I'm a bit of a Commodore gumby---I only ever knew one guy who had one, and it was a C=64. I couldn't find any of the cables when I bought it. I actually did go back this morning and found a few of them, so I have a few questions. The 1902 monitor has 5- and 8-pin DIN connectors. The C=128 has 5- and 8-pin DIN connectors for video, along with a DE9f for 'RGBI'. The video cable I found has a 5-pin connection labelled 'Computer' and an 8-pin connection labelled 'Monitor'. This sounds pretty straightforward. So my question is, which jacks are used for what? Will I not be able to use 80 column mode with this cable? Should I wire a straight-through DIN-8 cable and use that instead of the one I have? What do I gain by using the RGBI connector? Would one of the Tandy RGB monitors work with it? The thrift has one, either a CM-3 or CM-5. I forget which. Also, I was unable to locate the power supply. I notice it has the same connection as my A500 supply, except the switch is on the CPU instead of the PS. Could I use the A500 supply on the C=128 until I can dig up a C=128 (or even C=64?) supply? ok r. PS; I'm still trying to find info on that TI-99/4A video cable. (: