Is there any law or regulation that prevents this?

YES, you can transition from new copper to old galvanized, but just be sure the plumber uses the right fittings to prevent corrosion.  

If you are John, and the anchor preventing Sally from foreclosing, you might be able to buy her out cheaply if she doesn't know about the law change.

What are the best options to prevent from being heavily taxed from the W-2 job without the retirement contribution?

If more investors spend a fraction of the time and energy spent worrying about asset protection and do the things on a daily basis that prevents liability exposure, plaintiffs attorneys won’t eat as well. 

Insurance costs are going to be extremely relative to a list of variables that differ with every property, but if you know what to target and what to watch out for, these costs do not at all prevent positive cash flow on the right opportunities

Also, how does this anonymity strategy prevent a claim from being filed in the event a liability event were to exist? 

So, commingling these monies will likely lead to more of this down the road and prevent you from investing more.

It helps to prevent a tenant from doing what this tenant did and to give you remedies in case the tenant revokes the notice prior to the notified termination date.

I strongly believe that legislation should be introduced to prohibit property wholesaling and also prevent double closings unless it can be demonstrated that the property's value has been substantially improved.