I am NET cash flowing just over 1k (includes maintenance, repairs, cap-ex, vacancies, utilities), which is pretty good considering this is in SoCal.

Not to be a downer, but I'm not clear how I would utilize this metric to manage my properties. 

Avoid common pitfalls like underestimating costs or tenant management challenges by planning conservatively and staying proactive.

But usually for a tenant occupied it's like $90-120 per monthI've noticed a lot of multi-family buildings are pre-WWII housing inventory - are there restrictions or issues common with that (historic districts, crazy high utility costs, etc)?

  $31k after tax annual income - $11k rent = $20k or $1,600 per month net income left to cover all other expenses (utilities, cars, insurance, groceries, kids, activities, etc.).Median household income for 38128 is $41k or $36k after tax

A mortgage lien being the most common one.

If you have high holding costs (financing, taxes, insurance, utilities, etc.) the longer you are holding the less money that you are makingSelling profitably - How long will it take to sell?

This is a common problem for other places besides California.Most of my clients are out-of-state investors-California being one of the most common places for investors I work with.I would say, in general, it is very similar to in-state investing in that your investment is as good as the team you use.

I'll throw in my 2 cents on common differences I've seen in my career:CDFIs - Because of their subsidized financing structure, they have the ability to be a low cost lender (and sometimes provide grants).

While this is not common, its also not uncommon.