Skimmed through so I apologize if these were answered, but I didn't see it already.
To answer a couple questions:
Building is type B. Max payout is 7.2 mil. Type B pays out 30 times the base at lvl 10 and Type A pays out 75 times base.
To calculate total cumulative cost for a level use the following equation:
Let n be the level. Upgrades follow a geometric series with r ~= 1.67
Total Cost without modifiers = Initial * (1 - 1.67^n)/(1-1.67)
Thus, total cost without modifiers should be somewhere around 15mil * (1-1.67^10)/(1-1.67) = 3.754 billion
30% off: 15 + 15 * 1.67 * .7 * (1 - 1.67^9)/(1-1.67) = 2.632 billion
And so on and so forth.