1 hr service call +cost of material
I'd find another electrician or at least demand that he explain how/why this will not jeopardize your home.
The equipment - pump etc - should have a ground connector with the wiring if it is the plug in type. If the equp. is to be hardwired then a separate green wire should be pulled into the conduit from the source to the pump etc. In addition to that all the equipment should be bonded electrically. Your electrician will know what this means. By connecting this green wire as per code you should be Ok. However, this is a job for a qualified electrician who knows the codes in your area. As for connecting the metal walls of the pool - I do not know what the code calls for in your state for grounding or bonding this piece. k
Any electrician in your local directory or good diy enthusiast should be able to replace any thermostat in your home, be it part of a central heating system or household appliance.
If it ain't broke don't fix it
Electrode-chemistry, mathematics, metal chemistry and physics are good courses for a electrician to know in order to get full potential out of the work.
Because you will then get a 'galvanic reaction'.
go to an electrician
Experience and Track Record. This two should be on top of your list. There might be a lot of people with good written qualifications but without experience, they are all rubbish. You've got to look at how well they have maintained the quality of their service through the lens of those who have experienced it.
There should be a connection point on the appliance. This needs to be hardwired into an electric box, often with a disconnect or breaker. In some cases you can buy or make a power cord that plugs into a dedicated outlet with a mating connection appropriate to the voltage and amperage requirements of the appliance. If the service does not already exist, you may want to employ an electrician.
Call an electrician
You should excersie extreme caution when dealing with electrical work. Only a trained electrician should attempt to do this.
Yes, excellent idea, it's easier to fit, more lasting and often cheaper.