We have a reasonably high income from our W-2’s and rents with annual income in the $250k+/year depending on bonuses & OT worked and is usually closer to $300k.

All of this stuff will be dependent on the initial loan terms such as LTV. 

It will be highly dependent on the LTVs, but 2nd's on investment properties get sketchy. 

It depends on the area, and relevant comps.

Quote from @Joshua Tucker: What specific tax benefits can high net worth individuals receive from building real estate on tribal land?

Success still depends on your effort, discipline, and ability to execute.

While it seems like there are some better priced deals lately, you may have to be prepared to put down 30-40% down.I'd say due to the lack of homes for sale, you should be open to many if not most cities depending on the deal that comes up. 

I am a new investor looking for opportunities to invest in real estate, especially wholesaling, rental properties, and fix and flip.

It’s not a bad idea just depends how much effort and $ you want to put in.

@Mike Levene cost to build per square foot is $200-$300 depending on finishes.So, you can start with that.