Windows PCs tend not to have as long a usefulness lifetime as a Mac, unless you run Linux on them, in which they’ll run faster than ever and have a very long useful life span. Most folk I know with PCs suffer from viruses eventually, and also complain that their system is slowing down with age (just like people). In fact, Windows is notorious for declining performance over time as it uses a wierd, complex and inefficient method of storing settings and preferences - the registry, which is loaded at boot time. The registry grows over time as more software and updates are installed causing performance degradation. Also, you will need good antivirus software, which adds to the cost (unless you go with free versions) and also decrease performance and there’s no guarantee you won’t be infected anyway. A mate of mine spent a lot of money having his PC de-loused by a ‘professional’ PC clinic only to be infected again a short time later and he’s still paying annual antivirus subscriptions. He says he’s got a great routine, he switches on the PC on in the morning and then goes to make a coffee by which time the system is ready to use.
I would recommend an iPad if you only require general services like: web browsing, email and social media, online shopping, banking, photos, writing documents, etc. I would not recommend a Microsoft Surface as it runs Windows and I have no desire to use Windows. In the end, a Windows PC/laptop is cheaper initially but in the long run it can cost more, sweat and tears as well as cash.
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I agree with 1) but it's impossible for grandparents to say no sometimes. 
