My family used to manage mid-size apartment buildings and some managed motels and hotels; it must be in my blood.

I would suggest to partner with other investors, for building of that size a lender would go with 25% minimum down payment. 

As I have mentioned in other posts price them equal to or higher than the local laundromat for the same sized machine.

For the size of deal that you are looking to get into, I'm assuming that you will have a good relationship with your investor - I have several large investments both held in LP and LLC and they both work fine. 

I'm not sure on size of island I should do. 

What is the size of the property?

Mortgage brokers often throw a carrot of a really low rate out to engage the borrower and then half way through the process drop the bomb of them with a re-trade of a rate for X,Y,Z reasons.I would find lenders that specialize in your asset class and deal size as they will generally have the most appetite for it.

My parent's house (That I grew up in) was owned by some real weirdos that left the place in very poor condition.To this day, some of the places in that house will give me the willies if I'm there by myself.My wife, who is quite the logical individual, proposed that as a child (a very small child) who was already intimidated by the size of the house, I may have had some child-like fears of some of the spaces.Even though the house has been renovated, her idea is that something really subtle... like smell, felt texture, or even temperature may be causing a buried memory of those very child-like fears.Makes sense to me, anyway.

Back when my parents bought thier first house (because it was impossible to rent with kids, all rental ads said: no pets no children), there were small starter houses on good size lots that were designed so that they could be added onto easily.

Not sure how many units I could expect to get on that size lot.