Advice needed please

[Steve'o]

Hi everyone, I'm pretty new to all this and bought a used system on the weekend. Just starting to get it setup and needed some advice on the plumbing the guy had done.. see attached file? Is this ok for my FWLR reef setup that I am going to start? Is a 90 gal tank with an eshopps sump. I am going to replace the ball valve he had with a gate from some advice I got from another member, who also told me to get rid of the bio balls .. and just use Live Rock. Do you all agree? I have a skimmer also that will sit in the same area as the pump.
I would gather I will have the heater in the sump.. correct?
Appreciate any advice I can get from this knowledge base here.
Thanks all.
Steve'o