The 23-15pin adaptor only lets you use special "multi-sync" monitor, if your looking to use normal PC monitors you need a Scan doubler.
No, you can use a regular VGA monitor. Though you can only use the 31.5 KHz screen modes. This is how I currently have my A1200 hooked up. I initally had to use a TV on the composite outpost to set it to the hight frequency screen mode.
