Converting an unfinished basement into a third unit can definitely add value, especially here in Chicago.

I cannot comment is $100-120 is high as I do not know your market, and I do not know size of unit, bed counts, etc. 

Recognize buying rent ready units have very thin margins and most properties purchased off the mls will have negative cash flow.  

@John Lasheri agree with you, you'd be surprised at how many people listen to Grant Cardone though, and decide that they're going to go buy a 100 unit with 'OPM' as their first deal and quit their job.i think buying something of that size with a few partners is a perfectly good goal. 

So I've been thinking of joining the Air Force for 4 years, during those 4 years I would buy 3-4 unit properties which later after the 4 years I can get into Commericial real estate by doing a 1031 exchange or getting loans from private investors so that I can buy bigger multi-family properties.

There are 11 million undocumented immigrants in the United States.

A landlord policy can be a commercial policy or a personal lines policy.It's the same as asking if you should buy a single family rental or a 1 unit building.Focus on the coverages and disregard the name of the policy.

With a house hack you buy a single family and rent out rooms to roommates to make money OR a small mult-family (2-4 units) and rent out the other apartment(s).

I am a new investor looking for primarily multi-family properties with 2-4 units; would be willing to house hack as well depending on the opportunity. 

One of my recent favs is someone who's Instagram profile read  something along the lines "0 to 500 units in 6 months".