I also faced this dilemma while in undergrad school finishing up my Mechanical Engineering degree.

Most construction loans I am working with are I/O and some have the ability to turn to perm loans.4)For quickly evaluating a property and deciding if it is something to move on, I trust my own underwriting and my partners knowledge to see if a project will be feasible. 

If they have more people than agreed - you send them a bill or you ask them to leave without a refund, if that's what your rental agreement says (and mine does).

Other business interests/abilities like car mechanics?

See if it's active, inactive, expired, revoked, etc.Your ability to get the work permitted after the fact is possible.

I’m looking to setup a billing system for the tenants or use a 3rd party service.

Most REO deals prefer cash or private or hard money.So, many new investors think foreclosures are good because they are priced lower, but they are disastrous options for first-time investors as the inspection ability and repairs requests are limited to none and foreclosures also often times come with tax liens and other liens that may all not be fully disclosed at the time of the auction.If you are a first-time buyer and want distressed, you can look at HomePath properties which are Fannie Mae REO and they can provide a bit more protection to you as a buyer.

Especially if you're not doing it full time with access to the great deals first, the know-how to realize when you see a good deal, the ability to move very quickly and the crews to pull it off, it's going to be tough to get a home-run.

Whichever approach you take to investing or viewing the economy, I find that real estate, even more than other industries depends on your ability to connect and build trust with others.

You want to make a thoughtful, intelligent, sophisticated offer backed by the research, comps and evidence supporting your price and ability to close.