We once put in an offer on a property and the seller showed the agreement to "her agent friend", who balked at our contract and said that it was illegal to not use the standard real estate form used by realtors.

Is there a standard length of time that a GC needs to guarantee his work for?

It's the industry standard for amortization schedules. 

I have a chase card with a $23k limit that allows me to do "balance transfers" at 0% for 1 yr, provided you pay it back before the year (otherwise the rate goes up to standard credit card rates).

Are there usually standard amounts needed to invest personally, and approximately how much is needed for HML's. 

Attorneys are held to a higher ethical standard when self-dealing so it's probably easier for you to sue your attorney partner than vice versa.

Might have to babysit these tenants until they're up to your standards.  

Your standard NJ lease should have it take a look. 

Modulars are built to the florida byilding code standards, not hud/dmv.

All three of my rentals in Cleveland are in less than desirable neighborhoods, at least for my standards.