As you know bedrooms are worth more to appraisers than an extra living room.

So, the landlord makes an extra $1000 per month with the same fixed costs.  

Is it advantageous, or is it difficult and anti-foreigner with extra stamp duty and such?

Do an assessment of value now and after you get the ADU permitted * We have been in situations where $8k for permits could mean an extra $100k in value or $2k per month in rents. 

Just keep in mind that condos still have HOA rules and fees, which can sometimes limit rental options or add extra costs.

How much is that extra 5k worth when it takes 3, 6 months to get it rented and then you are over budget.

Other asset classes aren't so the depreciation schedule may not be as quick/beneficial.2) And it is even possible to find deals that are what I call "super-shielders" and which not only shield all the distributions in the investment but have extra to use over on other real estate investments that are throwing off income. 3) Unless you're doing a 1031 exchange  at the end or similar tax structure to defer taxes, you will have to *pay back* all that depreciation benefit at the end (on sale...which for you is in 5 years)  via depreciation recapture.

The reality is the opposite - if it's not in writing then the PMC doesn't have to provide the service or can charge extra for it!

@Mike Sfera, a few things about putting EXTRA money down on a property:1.

While I am extra nervous I am trying to make this an investing opportunity and decided to house hack or buy a place to rehab which I can later rent - let’s see how the DC market treats me.Suerte a todos y un placer !