So we did obtain similar result using different ways for the well of mana! That's a good sign that the numbers are self-consistent
For your second point, I chose Absolute Balance because in the game, mana and rage are treated on an equal footing, so it makes sense that both rage/mana = 1.5 runes. Also lvl3 wisdom requires 9 + 10 + 11 = 30 runes, even without counting scrolls that's 30/18 = 1.67 runes/mana. So in the end I use 1.5 runes/mana.