The plus one is sleeping on the couch or could be a baby in the parents bedroom in a bassinet.

Your liability insurance as a GC does not cover the building itself, the land and any claims which happen at the home ie; a child walks by and falls on a rusty nail and claims you are negligent, a contractor injures himself claiming it was the owner of the home's fault, the buyer of the home claims the LLC was at fault and misrepresented some fact. 

How about the child tax credit, exemption.

I currently rent in Brampton, where I pay $630 a month with all utilities included with some other nice perks.I’m a young guy and most people my age live with their parents, and some of my buddies have some properties already (condos in Toronto) that they rent out entirely for maximum return.It is from my understanding that legally you must live there for at least a year, no?

Since I am 24, live with my parents, and have very few expenses, I’ve contributed rather aggressively to my 401k for the past 1.5 years and have plenty of money in it.

Folks like my parents, who bought a house that needed improving back in the 80's, seem to be less common today. 

My parents almost bought a duplex in Richardson (or was it in Garland) but ended up moving to Virginia with me.

My parent's home is a custom build built in 2003 in a desirable neighborhood with above-average schools in a suburb in Buffalo, NY. 4 bed, 2.5 bath and 2,522 square feet.

Fortunately, my parents have quite a bit of experience in managing properties as they have had a few throughout the years.

It depends on the inheritance laws and how the property was vested to you grand parents (tenants in common, right of survivorship, etc) as to what needs to be done.