No, these will not fit on an AR or any picatinny/weaver rail.
Yes, the rings come in a set.
Unfortunately, the manufacturer does not have that information listed. We recommend contacting them for this inquiry.
You will need a set of 30mm rings for that scope, these Ruger M77 Scope Ring Set 1 Inch High Matte 90409 will not work. The Ruger M77 Scope Ring Set 30mm High at the link below should work. However, if you have a forward mounted picatinny rail on your rifle the objective lens may come in contact with it. So the rail may need removed.
https://www.opticsplanet.com/ruger-m77-scope-ring-set-30mm-high-blue-90407ru.html
The Ruger M77 Scope Ring Set are made of stainless steel and are compatible with 1" tube diameters.
The Ruger M77 Scope Ring Set 1 Inch High Matte 90409 comes with a Front #5 and Rear#6.
The Ruger M77 Scope Ring Set 1 Inch High could be used with a 50mm objective lens scope if it has a 1" main tube.
Yes, this has a matte black finish.
These will work best for that scope setup.
Yes, these should fit the Hawkeye M77 line.