Only just got my subscription so not an expert but I did lots of digging recently to set it up and the easiest way to cover all your devices is via a router yes, the other way is to download apps for each device and run a client on each one as and when you use it. I think the latter's main drawback is having to set it up on every device you want to use it on and have the overhead for the app and the encryption on that device(not sure what that will be) as well as if you are the only techy in the flat/house hoping others will be able to learn how and when to use it on their devices.
The only problem with the router to cover everything is you get one connection which will be anywhere from 20-50Mb/s to share amongst all your devices, most VPNs give you multiple device slots(think Nord gives you 6) so sometimes it might be better to do it per device, if only there were a way to have multiple connections on one router taking up those device slots it would be perfect.
As for routers your new router would connect to the superhub(which is a cable modem router rather than just a cable router), I have mine set to modem mode because the features and security are very limited on the Superhub that way everything connects to your newer better router and the Superhub works happily as just a modem. I have been thinking about having a dual router setup that way you could have the new router for the VPN and the Superhub would be your normal full speed connection, you'd still have to remember to switch connections accordingly though.
The router would need a half decent CPU and enough ram to run the firmware, client, encryption etc required: 1GHz and 128mb is what I've typically seen recommended and luckily I was already using one capable. Just google "VPN router" with DD-WRT or Tomato and take your pick. I wouldn't go too cheap and I'd read the forums(DD-WRT and Tomato will have sections for most Routers they support) to make sure it does the task well from other users opinions before buying.
Most recommend Asus(Nighthawk) well built, nice and fast and stable but they are pricey, TP-Link are great value for money IMO.