U want your parents to talk to their CPA FIRST.. if they go the development route they are now ( depending on the amount of units) creating inventory.. which will be taxed at ordinary income rates ( very HIGH)if they just sell they can 1031  and move on to something else.. many times when you run the math consider the risks of a partnership.. the sale of the land is far better than thinking your going to make some profit.. 

Of course, nothing is stopping you from selling Rental #1, paying taxes, and then taking your leftover after-tax profit and moving that into Rental #2. 

If you've lived in that house 2/5 years as your primary residence, you can also sell it tax free up to $250k single/$500k married-filing-jointly. 

Here are some considerations and normal practices to ponder: Employee Structure, Contractual Agreements, Insurance Coverage Benefits, and HR MattersLegal and Tax ImplicationsCommunication  and Collaboration.

This sounds like a live in flip, which can be a nice way to get some tax free capital (if you live in it for two or more years).

Concurrently, I intend to construct our dream home on an adjacent 20-acre parcel that I already own outright.I've double-checked the property taxes, and they're not just accurate but slightly on the higher side.

If you bought it for $450K and believe it is now worth $550K (get a realtor to confirm that), think about capital gains and taxes when you sell.  

I’m a 25 y/o Dentist in Canada, thinking of specialising in the US (2 year program) and live in the US afterwards.Any fellow Canadians here that can give me a general idea with tax/setting up corp and all for US RE journey?

Tax implications?

Mexico has a lot of great architects and the quality of the construction in the higher-end of the market (in which foreigners and upper middle-class and wealthy Mexicans buy) is very good.