Hose to Hydrant

My water pressure fluctuates between 75 and 95psi in about 15 seconds during the day. No water running in the house. You can hear the water heater popping as it expands and contracts. I'm tired of worrying about something breaking, so have decided to install a PRV. My incoming water line is 3/4 copper and I am looking at a Cash Acme EB-25 that has sharkbite connectors on each end. Since that is the size of the sharkbites, I assume that would be the correct one. There are two of us living in a 2000 sqft house. Your opinions please before I buy it. The only negative I see is the price of the repair cartridge.

Could someone please tell me by pictures what size valve is this? In coming from pipe and outgoing to washing machine. I think they are 1/2 incoming and 3/4 outgoing. [ATTACH]93739[/ATTACH] [ATTACH]93740[/ATTACH] There are thread on incoming pipe. Are these threads on the pipe and there is an adapter soldered to pipe. What kind valves should I replace with? I have these [URL]https://www.homedepot.com/p/Tectite-1-2-in-Brass-Push-to-Connect-x-3-4-in-Male-Hose-Thread-90-Degree-Washing-Machine-Ball-Valve-FSBWMAV/302161124[/URL] I have 3 questions. Q1. Are ball valves any better in terms of functions (not leaking) and longevity over globe vales (what I currently have)? Q2. New Valves are sharkbite valves [URL]https://www.homedepot.com/p/Tectite-1-2-in-Brass-Push-to-Connect-x-3-4-in-Male-Hose-Thread-90-Degree-Washing-Machine-Ball-Valve-FSBWMAV/302161124[/URL]. They require smooth pipe. How should I do it? Should I buy a female adapter like these [URL]https://www.homedepot.com/p/Everbilt-3-4-in-Copper-Pressure-Cup-x-FIPT-Female-Adapter-C603HD34/100347144[/URL] and these [URL]https://www.homedepot.com/p/1-2-in-Brass-CSST-x-FIPT-Female-Adapter-11-435-005/203073898[/URL] Q3. If yes then what size should I buy? 3/4 incoming water side and and 1/2 towards sharkbite valve? Do I need to buy a new box to get a better access to pipe? additional enlargements.... [ATTACH]93741[/ATTACH] [ATTACH]93742[/ATTACH]