Does anyone know if you can use a cost segregation studies for STR properties that you may have outside the US (and use it against your US W2 income)?

Your resident based will be much more stable, turn costs will drop.DM me if you have any questions. 

Is there any requirement that I notify the lender that the property will no longer be my primary residence?

Property ARV: $450kTotal in: $350kMonthly rent: $4000Monthly taxes & insurance: $530[Loan 1] (via broker)75% LTV1.5% origination fee ($5062)Other fees: $1595 underwriting + $1295 processing (=$2890)Interest rate (floating): 7.25%5 years PPPMonthly P&I: $2,278Rent - PITI = $1,192***If appraisal comes back high enough, may be possible to do 80% LTV at 7.99%[Loan 2] (direct lender)70% LTVNO origination feeOther fees: $1,395 underwriting + $695 processing (=$2090)Interest rate (will not change): 7.375% 5 years PPPMonthly P&I: $2,152Rent - PITI = $1318---------------------------I really like how there's no origination fee with lender #2 so I get to keep more of the money I pull out.

"The true measure of a man [person] is how he treats someone who can do him absolutely no good." - Samuel Johnson This post is intentionally short. 

I could also refinance before 2 years is up but closings costs for apartment buildings are expensive right?   

Just buy a 4 unit 25 down in any class A/B area and you will do great, no need to do commercial loans, big rehabs, etc. atleast at first. 

No problem right.So what do you do when you find out the borrower is in prison and the 17 year old daughter who is a junior in high school is living in the property and she is trying to find a place to live with a friend and needs an extra 3 weeks.

no one does.so maybe do both. 

It demanded to replace full flooring, scrape walls and repaint costing entire year worth of rent from that unit.Question: are there technical solutions inexpensive to remove cat urine instead of replacing all wood , carpet and walls?