I have done extensive research on REI and am sure that this is the career path I want to take.

There is a property I am eyeballing that would require a fairly extensive remodel, but it is also big enough and laid out in a way that made me think it might be a good idea to convert it to a duplex. 

This type of deal works best for highly distressed properties that need extensive repairs, major remodeling, or a total gut.

In my immediate vicinity (area that I worked extensively) and did most of my business in there were 2 subdivisions on acreage lots .

On your 1st Question, As for Now, Stay away from anything that needs extensive renovations.

Make sure you do extensive due diligence. acquiring tax property owned by the county can be had for 50 cents on the dollar or less at times but the tax sale does not whip out all liens. i.e.

This is covered extensively on Bigger Pockets.

Then the second month, one of the tenants asked for extensions on the rent.

I have yet to have a new build ever be done on time (which leads to problems moving out / renters moving in, and expensive interest rate locks extensions), 7 times out of 8 it ends up costing a couple points more than expected, so yeah, building a house isn't the coolest way I would try house hacking.As a side note, I've had an accessory apartment. 

Make sure your agent is on top of any extension request necessary to complete the deal.