Ok, lets see if we can make this less stressful.
First off, I am guessing that the cmc is used by zooming all the way out, and using that for macro (P&S lens normally have their macro with the lens at the widest field of view). If so, then one gets a greater working distance, but that is true with any wet lens. Usually, it is best to have the lens as close as possible to the macro lens (which can be zoomed out or something close to being zoomed out, just watch how the lens move as you zoom)
You need enough working distance to protect your port and allow you to get lighting on the subject...so around 2 inches (or 50mm) is a very good number. Depending on the port size, you might be able to go down to around 40mm or so.
If you had the Saba, subsea and SMC, you can actually see the difference between a high contrast and low contrast lens. Higher is better with contrast detection systems. All can take very nice images..but the lower the light, the less clear the water and the lower the contrast can make focus more difficult. Higher is better, but all work for at least 70% or more of the time. Saba was the worse, subsea next and SMC the best I have used (so far). This is a glass issue for the most part. It was easy to see the difference between the SMC and the Saba, but not so with the subsea.
I think Aquako, used the same as the CMC should produce very similar magnification (a bit better) and should work fine. I would go with that for now.
Learning to use a high power macro is a bit difficult unless you have had a lot of experience with weaker ones, so everyone will have a steep learner curve. Just have fun and enjoy. Oh, and remember..start with the camera lens as far out as it goes....use the highest F stop you have and move the camera first to get focus. After that, it is practice.