Microsoft's previous attempt was just software. Apple spent 15 years designing their own SOCs, bought several companies in the process, including a fabless fab. Apple has always been in hardware, they are the A in ARM (not that it's an acronym).
Yes, but they must either build+buy it in 10 years or buy+build someone else nearly there and hope to get it done in 5.
What success?
I think there's nothing wrong with running Windows on ARM, but the problem is that Apple's ARM chips are capable of desktop-grade performance and other ARM chips aren't.
If PC vendors like Dell and HP can get better-performing ARM chips then you can run Windows or Linux on them. Until those chips are available, desktop/laptop ARM is going to be a disappointment -- because of the hardware, not the software.