12%, IRR is the return to zero NPV for a series of cash flows
Yes, you should include the debt service (I believe, 80% positive here, hopefully someone else chimes in)
Net Income/Equity. You only have 25% equity, so that is your denominator… Net Income for a property is calculated as NOI, which would be NOI/PP = Cap rate. If you just use 100 as the PP, ROE should be around 16%.
Not familiar with amortizing loan constant, sorry.
In regards to #2 I think Debt service costs aren’t included. I remember reading to assume that projects are all equity funded. Not sure if that was for a specific type of project or what.