Not only was that a wise financial decision, but it allowed us to get a primary house (which has since been Section 121'd) AND our first rental. 

Would give me a better idea of whether it would be a wise investment, as the four other tenants pay less than $1,000 per month on a 2 bedroom apartment.

Can someone, or is it wise for someone to purchase a property under an existing S-Corp that was set up for something else?

If I were to offer higher than asking price to lock down the deal, the only thing that would change expense-wise would be my P+I, but that would be minimal. 

Economy wise we don’t know which way this thing will go?

By having a reasonable, risk-adjusted investment strategy that involves discipline and patience you can invest wisely in any market.

If you have less than a 1-year experience and no obligation on your credit report your personal income must cover the $500 dollar mortgage payment for DTI purposes.So, depending on your unique situation there's 3 outcomes DTI wise. 

I'm conflicted on the best way to approach my first deal funding wise.

Be very conservative with how much you can get rent wise. 

In light of that, is it still wise for me to buy US real estate?