Yes, there are different types of shut off valves depending on how you want to install the, water supply diameter. Ask your plumber if it's not making sense. I assume only have one water supply line to your house so you wold only need one.
The hub and sensors are critical for alerts, notifications and telling the shut-off valve to close. How else do you propose to turn off your water supply in the event of a leak?
For Leaksmart to work you must use their sensors. As I said above, for reliability reasons I would not attempt to get this to work via Control4.