I'd recommend sticking to duplexes and triplexes. 4 units are considered commercial by building standards and have higher scrutiny.

I would recommend working with a good investor agent who can help with all of this!

We simply include the tax on the invoice sent to guests, which makes it easier to track and ensures we're covered for tax purposes at the end of the year.For Chicago, I’d recommend checking directly with the city’s tax office or a CPA, but generally, you’ll need to register with the city, collect the hotel tax from guests, and remit it on a regular schedule (likely monthly or quarterly).

If you will be financing this purchase, I recommend starting with a prequalification as they will really help you focus on what markets will serve your budget best.

A DSCR loan is going to require more down, have high fees at closing, a higher interest rate, a pre-payment penalty, and will require you to have cash reserves that you likely don't have at the moment.

Or is he requiring a down payment?  

I would recommend that you focus on which area you want to eventually settle down in.

I recommend speaking with @Denver McClure to see what is available given your situation.

I'd recommend looking at costs. your build cost is going to be well over other homes because of the fixed costs like slab, Hvac, roof, etc. check the market drivers and weight the benefits of short term versus long term. long term is no furniture and help pays mortgage but at this size it doesn't really cover everything. we didn't find a lot of economies of scale in single family detached. can you build more than one unit?

To answer your question I would highly recommend shopping around on the BP online bookstore and finding a couple of books that stand out to you.