Sounds like a joke "Kaspersky, Webroot and a Hitman Pro walk into a bar...." But hey! If you can afford it and they do not conflict nor slow your PC down -- why not? IMHO one KIS is enough. but, hawki for a period of time had that same combo on his PC. But removed Webroot, fearing that under the hood it might in some way conflict/interfere with KIS. Webroot and it's legacy product - Prevx - used to make a big deal about being compatible with most A/Vs, but dropped that as a major marketing point as Webroot became a more refined stand alone solution. You still might be able to find on The Webroot site it's list of compatible A/Vs -- not sure if it's still there. IIRC just about every major A/V was on that list.
Yes, it is. Unless you don't use an adblocker as uBlock Origin and download and click in every BS that see, Windows Defender, a backup and one or two on demand scanners is more than enough.