while I am not familiar with the IBM P260 monitor (CRT), my guess is that its gamut is very close to sRGB color space. This will always be the maximum gamut regardless how you calibrate your monitor. The size of the gamut is defined by phosphors that were used by the manufacturer. For CRT displays, available phosphors give you gamut similar to sRGB.
Since you have chosen the color temperature of 6,500 K you at the same time have the exact white point of both Adobe RGB and sRGB color spaces. In my experience, the presets of white points (D65, D50) do not necessarily give you the desired "true" color temperature (6,500K, 5,000 K). So the Expert mode would be more appropriate providing you use a colorimeter and the corresponding software. As you are aware, manual calibration based on subjective judgement of gray or color patches is not reliable way to calibrate your monitor. You want to adjust contrast, brightness, and gains for the RGB guns. If you do not have any calibrating device available, I would use the Easy mode with sRGB preset. If you see a bluish or yellowish tint in whites, I would go for harware calibration.
The workflow sounds correct - I assume that Photoshop is set to sRGB color space. Having no icc display profile, your computer system defaults to sRGB color space as far as the color output is concerned. If your monitor is calibrated to sRGB you have about the right setup.