For the “how much water to add to the cubes” question, I find that I can soften the cubes without soaking them by putting in enough cubes to cover the bottom of the feed pan in a single layer. Then cover with enough hot water just to hit just below the top of the cubes. Leave to soak for a while - I make them up at the previous meal. When I get back, they have soaked up enough water to soften completely but are still kinda flakey and more damp rather than soaked.
This probably is not making sense, but the point is to use less water than you think you need, and give it more time than my usual 5 minute soak in hot water. With enough time, the cubes will soften in a smaller amount of water.
I use Standlee cubes, in case it matters.