I’m looking for the best ways to build my FICO score.Most likely, it will be a secure credit card, but do I need to have a US address in order my FICO score?

I've build a lot of equity in one of my properties and I am thinking about recasting to lower my monthly payment. 

And switching back and forth will cause you to lose many years of tax deferred gains.But you're starting out and trying to get traction to build. 

I’m wondering if anyone has advice on how to get started or if I should wait and keep the money in the stock market and diversify to other  investments to build up more cash.

Apartment complexes and commercial buildings  always carry this but it's also common with residential.

Getting started is as always the hardest part - building out the logistics, legal bits (for import duties, etc), marketing (be it a website, direct b2b marketing or Amazon) and sourcing the right suppliers are all equally difficult (yet interesting) tasks.

Advani suggests that a strong focus on professional property management can significantly reduce the risks associated with real estate investment.Construction and Development InsightsFor those looking to invest in construction and development, understanding the ins and outs of building projects is essential.

Go into your building department and verify as well.

There is a small chance I keep this one and continue to build the portfolio. 

You can build up goodwill sending grocery cards at Christmas, having a mini fridge to rush over the moment there is a problem, giving rent credits, etc. and it will mean LESS THAN ZERO as soon as you have a late fee you expect them to pay, a pet that you cannot approve, anytime the rent goes up, telling them they can't paint the walls and ceiling the color they want... then you are the scumbag landlord.