A reliable unit will specify the flat loss imposed by the circuit.
And with every connection there is what is called 'insertion loss' that quantifies the effect of a physical connections efficiency.
How much insertion loss is experienced, check the unit itself. This, alone with the signal to noise (S/N) ration will (should) be specified.
As far as will fancy coax somehow mitigate the upstream source typically consisting of a possible microwave link to a sub head-end, trunk line, feeder lines and cable drop, and assorted ground blocks, splitters and distribution runs inside the house?
I don't know of any interconnect of any kind that can restore something that has been lost. They are not program sources. The best they can do is reduce additional degradation.
The best coax is consists of a double foil double braid configuration, with the braid being dense. This makes the cable less flexible and less able to make extreme short bends. This configuration was originally developed by Belden for Viacom Cablevision in the early 1980's as they were working on the deployment of the first totally addressable two way systems and remains the best cable.
Is it necessary in a house for short runs? That depends on the degree of RF/EMI interference present. If there is much, then its worthwhile to utilize the maximum rejection possible. If not, then its overkill.
In any case, are you going to notice a dramatic difference. Most likely not. You may notice slightly less noise or spurious interference, but as far as the program material itself, there will be negligible difference in picture quality and flat loss for such a short run.
And if, after they install the system, you experience excessive noise, then get them out to troubleshoot the line. And if you insist on using your own gear, realize that they will not support this, and the onus will be on you to demonstrate that the problem is one of THEIR making and not yours. And realize, that the majority of problems encountered in such situation are due to the customer going to Home Depot or Lowes and using splitters, connectors, etc., that modify the distribution impedance via improper crimp tools used for fittings, as well as splitters and AB switches that not only exhibit loss, but generally do not exhibit the same S/N characteristics (typically a difference of 60 dB versus 90+ dB noise figures).
Thus, the most you can expect is to maintain the quality of the signal that enters the house.
And yes, it is worthwhile to protect devices from surges on BOTH the AC and tuner inputs.