The loan converted to a standard mortgage after the rehab was complete, so no need to refinance or do a second closing. 

In a standard 40 page finding I will pull out 1-2 things that should actually be addressed and even those things usually aren't deal killers.

There is no standard.

There can be exceptions, but that is the standard deal. 

Standard requirements for such investments typically include good credit, relevant experience, and a 20% down payment.

This can add up.Property Standards: The house has to meet certain standards, which might limit your choices in a competitive market like LA.Loan Limits: There’s a cap on how much you can borrow with an FHA loan, which might not cover the higher-priced homes in LA.My Take:If you’re set on buying now and can handle the extra costs, FHA could work.

Any calling themself any kind of "Pro" or "experienced" buyer of any ilk really worries me if they don't know this, it's that standard. 

Some things that might be a concern:1) Obviously have to make sure things are all permitted first2) I don't want the room to "feel" like an addition, so flooring has to be same level/standardized with the rest of the house3) Unlike the rest of the house that has an identically-shaped 2200sqft basement underneath, this added space will not have a basement directly underneath it -- I'm not sure if this poses major cons for some reason that I'm not aware of4) Especially given the lack of basement underneath, I have to make sure that the HVAC can still somehow be piped into this room#2 and #3 are probably my biggest concerns (#1 and #4 I can find out relatively easily)Any tips/thoughts or other experience would be greatly appreciated. 

“Broker” is a legal term that often requires standardized coursework and a state license.

In short, I wouldn't be doing this without him.However, your comment did register with me as I should have researched more about what is industry standard before getting started.