If I'm bringing in a contractor to solve a problem -- need an engineering solution, need to reroute a plumbing line, need to fix a foundation issue, need a kitchen layout along with the cabinet installation, etc. -- then most certainly those are situations where you want to consult with with contractors 1-on-1 to determine not just how much it will cost, but what specifically should be done.But, situations where I want/need a contractor to solve a problem are less common than situations where I already have a specific scope of work, and I'm just hiring the contractor to carry out that scope of work.  

You can also verify via the Florida licensing website and going to "Construction Industry" in the drop down, which will create another dropdown where you can select "Certified Plumbing Contractor"; I'd also have him provide a copy of his insurance, but that's me.

Ditto kitchen rehab, new windows, new plumbing, near roof, new HVAC, new stucco/siding, etc.I suggest you attend some REI meet ups.  

I haven't checked the PA one but there's probably something similar.5-12-040 Tenant Responsibilities(c) Dispose of all ashes, rubbish, garbage and other waste from his dwelling unit in a clean and safe manner; (d) Keep all plumbing fixtures in the dwelling unit or used by the tenant as clean as their condition permits; (e) Use in a reasonable manner all electrical, plumbing, sanitary, heating, ventilating, air conditioning and other facilities and appliances, including elevators, in the premises;

He says we're good to go except there is an open plumbing permit that needs closed out - says the plumbing inspector probably just forgot to do the paperwork.

That 600/month will quickly evaporate with your first pest control and plumbing call.  

Need to redo the plumbing and take out the copper pipes in my 3 family house I recently bought..... how much should I expect it to cost?

However, if your renter has rented from an apartment community in the past that is professionally managed, it is likely that they've had the clogged toilets as a service their maintenance team would handle.Along Chris's point, you don't want your resident fixing plumbing issues like broken sinks and toilets because they could make the problem worse. 

Just recommending you verify electrical and plumbing systems are up to code.  

as an electrician I am wondering what year this is and how you estimated the electrical/hvac/plumbing costs.