ye windows defender is honestly good enough for day to day surfing, and even then, free anti-virus like AVG will do the job fine if you want something a bit extra. you don't need to pay for anti-virus
Yeah, these days there is really no need for anything more than that. If you're visiting potentially sketchy sites then you'll want to have something like NoScript in your browser but otherwise Windows Defender does the job just fine
windows 11 is basically 10 once you lobotomize it and force it to stop trying to put ads and tracking everywhere also, yeah, i had zero adjustment period needed