I can't imagine a legitimate roofer doing this without alerting someone to the condition of the OSB or plywood underneath just to cover their butts.I guess the real question is was this a licensed roofer or you know....... just a guy?

Everyone I consult says it depends and that I must hire an engineer and do soil testing, etc. in order to get an accurate number. 

CPA - Designation by a state that normally requires 120-150 credits at a University(4-5 years), completion of 4 exams involving tax, audit, acocunting and law, 1-2 years of work experience underneath a CPA.You are also required to take continuing education every year.This professional will normally provide a range of different tasks such as Accounting, Taxation, Assurance or consulting. 

Also the gas valve is directly underneath the pan, so not sure how far the pan would drop.  

The underlying soil sliding on bedrock.

Site development, is custom, grading, soil prep...the list goes on.

A few partners and I are looking to put our money together and buy properties underneath a joint LLC and build a business. 

I stick the hooks to the board, write the unit numbers underneath (no addresses) and screw it to the wall.

Soil?  

When I bought my 4-unit there were rat turds all over one vacant unit - in the two vacant units when I looked underneath the sink I discovered there were large openings for the piping beneath the sink.