Mold, critters, and everything grow year round. 

Your debt to income is a ratio percentage of your debt against your current income...For example if your monthly debt total being mortgage, car loan, credit cards, personal loan, student loans ect... you would take that amount and divide it by your monthly income, and that will give you your DTI ratio.Example:$3000 debt / $7000 income = 42.8 rounded = 43% DTI This ratio is what lenders use to see how stable someone would be in paying back a home loan.

If the bonus depreciation rules are extended then you will have the option to repeat this exercise down the road rather than do a 1031 exchange. 

If he bought a property before 1 Jan 21 (I know, tough), would bonus depreciation help?

If our friends lived with us it would be an added bonus.

I go into these flips thinking they will be full gut rehabs, and if we can save anything it's a bonus.

If you want to incentivize, you can offer a bonus based on the timeliness of the completion of the reno. 

It is an area that is STR friendly and rental demand is fairly strong year round (a little soft early winter and spring).Looking for some general advice and some helpful answers to the a few questions.   

I'm looking at a multifamily 4 unit with a "bonus" basement unit in Illinois. 

Buy it based on the current number of units, and if you can add one more in the basement then consider it a bonus, but don't base your offer/purchase price on the assumption you'll be able to do so.