What can happen if I flip off a cop?

Perfectly legal. But doing that might lead to the cop paying more attention to you. And cops sometimes are no more mature than you seem to be.

A multi zoing area/ light industrial, currently a house on one acre . the house is occupied by a family ,

Probably, depending on how big your property is, how many buildings the county allows on a one acre parcel. You need to talk to the planning...

You could appeal. You may qualify under a grandfather theory. You really should contact a local attorney.

Questionable construction contractor?

The contractor's documents are not necessarily improper or questionable. Those may be his observations or what was reported to him by the...

How can we sue the landlord of a neighboring 4-plex that is creating an unpleasant, illegal and immoral environment?

If you witness criminal activity, you can report that to the police and the city. If they get enough complaints, they will eventually take action...

What are my rights regarding a neighbor who has made threats, and did not show up for a hearing with the city atty.?

You should put pressure on your landlord to do something. If the property is large enough, perhaps he can move you to a different unit that is...

You probably can't do anything. You could potentially seek a restraining order or injunction, but under the facts you provide, I doubt you would...

Should I call the police if my tenant denies entry during a maintenance emergency?

I agree with the other answers. As a last resort, if you can't get access, you could try shutting off the water. That could lead to claims...

It may depend on your cc&r's and HOA rules and regulations.

Do I need to file a copy of the stop notice at the nearest county courthouse in the same county as the project?

The other answers are correct. You do not need to file the stop notice at the courthouse.