The problem is I'm worried about buying this house from him because he has a fiduciary duty to get his client the highest price; but would it be proper/common to ask him if he'd be willing to find other properties for me and act as my real estate agent in a buying position? 

Also it seems common that the smaller local banks and credit unions are more flexible in their financing and underwriting as it appears you are doing

Jumping from 0 to 14 in one year is also common on these forums.

Multiple offers is a common strategy with wholesalers and investors buying off market.

This is a common practice (at least around me), and people are always willing to share what they know.

Note: this year there was a change in regards to evidence of termites and treatment so if at all possible you will want get proof of treatment from the current owner and give it to the inspector before the inspection.

Assessor valuation, appraisal are some of the common methods.

What are the most common reasons for delays? 

HELOC's are much more common on primary residence properties.

350 is a pretty common temp for baking.