Hi,Once I get work completed, who should I use to verify that the work was performed well other than myself?

My first thoughts are why is the property performing poorly?

There are 2 areas in San Diego that I believe are likely to out perform the general San Diego RE market (and I am not invested in either due to distance from my base).  1) west Chula Vista (CV).  

What key factors should influence my decision on whether to sell now, offer seller financing, or keep the property as a long-term rental?

Tell the agent what you need done, and if he doesn't do it in a timely matter there will usually be a clause explaining how you can terminate early without penalty if he fails to perform or do his job to the best of his ability. 

Every property in a location can perform differently based on many different variables.Just find properties you like and evaluate them individually. 

As Jaron mentioned above, average homes aren't performing well and the unique, experiential homes are hitting and exceeding revenue targets. 

A Self-Certified permit review would likely only take a few weeks; as compared to 4-6 Months for a project which is not "Self-Certified" and needs to go through the "Standard Plan Review" process.A Zoning analysis should be performed for your property ASAP using a Plat of Survey to ensure you would be allowed to build what you want to build, and check for any potential "Setback" concerns when it comes to adding Dormers...

It may make evictions of non-performing tenants difficult or impossible.

You also haven't provided any numbers about ROI or cashflow - how good are these properties performing?