The Hunters Specialties Choke Tube Undertaker Rem 20 Gauge will not work in a Benelli Nova. You will need a 20 gauge Benelli Mobil choke for the 20 gauge Nova. The choke tube at the link below will work for that shotgun.
https://www.opticsplanet.com/carlsons-20-gauge-benelli-beretta-sporting-clay-choke-tubes.html?_iv_parent-gun-make=benelli&_iv_parent-cartridge=20-gauge
No, this will not be compatible with the choke system on a H&R Pardner Pump. The Pardner Pump uses the Browning Invector/Winchester/Mossberg choke system. The version of this choke that will be compatible with a 20 gauge H&R Pardner Pump can be found here: https://www.opticsplanet.com/hunter-s-specialties-choke-tubes-00666.html
Yes, this should be compatible as long as it is one of the 20 Gauge models.
No, this choke is meant specifically for lead and copper plated shot per Hunter Specialties description.
No, your shotgun uses Winchester/Browning/Mossberg pattern chokes, so you would need this option instead: https://www.opticsplanet.com/hunter-s-specialties-choke-tubes-00666.html