I would be putting 20-25% down and use a loan to get more for my money. 

There is still money to be had and a lot of opportunity but just make sure your location is good.

I think you may want to start of the arrangement in a more simple fashion.Ask for a loan in which he will get a stated return 6% to 12%.If you are both successful happy with this arrangement, upgrade to a partnership.I think a partnership off the bat makes things complicated.You will also likely make more money in a loan agreement if the project does well.

I was intrigued by the fact that you don't need a lot of money upfront to get in.

We currently have some money that we could use for renovations, but we don't know if we should use the equity for that instead or use it to put it on a different property.

You can even get better with CDs and money market with no risk.  

That's a lousy spend of money.

We have a relationship with a much larger developer who does multifamily, mostly apartments, and even they can't figure out where to put their money right now, because the math just aint mathing for them to build or renovate at the moment.

There are no fees each time you draw. closing costs are often minimal, and the rate is similar to a hard money loan.

What I can say though is that Portugal will tax your income first either by having the OTA withheld the tax from the money you get or by having you make a local tax return.