But if someone pinned me down with a gun at this moment, I would say A property is high neighborhood, high desirability, B property is good quality working class neighborhoods, C property is lower middle class and fringe neighborhoods that are either just declining or are just coming back, D property is lower class property in undesirable areas but houses are still standing, and F is war zone material.

Some still say a great investment. 

Neil,Commercial sales commissions typically (and I would say as a caveat this is market dependent) reduce in % as the deals go up in value (think 1% of sale price on deals $25 mil+).Regarding flipping or build & sell - in my opinion a commercial flip or build & sell would typically involve leasing and lease commissions.

However...There are a lot of critics that swing one way or the other - many say a Trust is not needed if it's in an LLC, and vice versa, so form your own opinion based on what you see and reach out to your real estate attorney to come to a decision.

However, when you move up to bigger and better assets you'll want to structure them differently from say, a SFR...  

If you write with an 8 day inspection contingency, and your inspector identifies issues requiring the services of say a foundation expert, and that can't be found until day 10... extend it, tell the seller side why.It may be different in the Bay Area.

You should say a little about yourself.Are you willing and ready to buy?

I'd say as you get started, just be sure you are up on running numbers.

Or is it each individual housing space in say a duplex, triplex, or fourplex?

Does anyone know what rate a 580 credit score would get versus say a 620 or 720?