It depends on the product.  

Not sure how much, some of it depends upon what your limits are but depending on how many cards you have you’ll get a bump with each one that’s paid off.

In Mass, the zoning laws vary from town to town and can be very specific.

Depending on the strategy MANY technical skills can be involved from the trades going rehabs and repairs, legal, financial, project management, etc etc.

I would expect a 7% appreciation in property value per year is also a feasible target - this is dependant on where you will be living.I have found multiple properties that are close to fitting this build for another client just this week.I would be pleased to connect with you to discuss further if you would like.Respectfully,Chris

As long as you are negative cash flowing less than what you would be paying in rent, it makes sense (this depends on your market; I am in Austin, and nothing here has positive cash flow).

 There are advantages to both depending on your situation.

This probably depends on the level of sophistication of your investors, but I would consider this a kind of "incremental analysis", similar to an incremental IRR calc that could be run on a staged investment. 

So it depends on your goals and what you want to accomplish. 

Typically investment properties requires 15%-25% down payment depending if it's a single family or multifamily.