What is PMI?
PMI, is Private Mortgage InsuranceYou need it because a bank takes a higher risk with less money down. Most lenders require 20% down to avoid PMI, and the rate or cost is going to be associated with the credit risk of the borrower assessed by the bank. You need it to ensure that the bank won't lose...

How are high-priced homes financed?
It depends on the area as well. In short it is like conventional financing however the loan to value tends to go down as well as the debt to income requirements go down as well. There are a variety of companies that will finance out side the box as well, some will even take pledged assets.

Can someone get a reverse mortgage if they already have a mortgage on their house?
Yes, it will depend on your age and value but you can refinance those two loans into the reverse mortgage

Minimum downpayment for an owner occupied triplex?
You can do as low as 3.5%.