Tax situation for person leaving to home country after 10+ years in US in H1B

[ursvasan]

I have lived in US for >10 years and I still don't have permanent residence or citizenship. 

I bought a home in 2014 and I have been living there since. once i move out, I am planning to rent my house for couple of years till i decide if i want to come back to US or not. 

Rental Questions

1.Given that I would become a Non resident alien for tax purposes once i move out, what will be the tax on the rental income? 
2. What are the things i can deduct in my taxes. I am going to pay a property manager, have some maintenance expenses and also pay the mortgage for my property. Given the mortgage, my net rental income can be negative if i have some big maintenance issue. 

Other finance questions
3. How will Long term capital gains work once i move back to home country. If i stayed here it would have been 15%? Does it change if I move back ?

4. Can I still buy/sell stocks in my US trading account ? will there be any issues with it ?

[RSUMan]

1.  You will have US source income relating to the rental property; you file a nonresident alien tax return using our partner Sprintax.

2.  Your rental may in fact generate losses with interest expense, property taxes, and depreciation (please make sure you set the asset up correctly and calculate depreciation of the structure correctly; you do not depreciate the land value).  All of this becomes important if you sell the property.

3.  Your holding period of the house already exceeds a year and a day so any gain will be long term.  Your foreign residency has nothing to do with the capital gain rate; the capital gain rate will be whatever Congress says it is in the year you sell it.

4.  You can still buy and sell stocks in your US account; however, the brokerage will issue a Form 1099 B with your dividend and gain loss activity tied to your Social Security Number and you may well have to report that on your Form 1040NR.

[ursvasan]

My rental cannot cover the mortgage + property taxes (let alone expenses). But can i deduct principal amount from the tax ? I am in 15 Year fixed and the mortgage is higher. Can I also write off expenses for property management, gardener, repairs, etc ? 

Do i fall under a higher tax bracket just because i will be a non resident while i am out of country ?

[RSUMan]

The amount you pay the mortgage company for principal is not a deductible expense.

Amounts paid for gardener, property manager, and other ordinary and necessary expenses to rent the home are deductible.

You will not be in a higher tax bracket as a nonresident filing a tax return.