Don't know about Apple, but for Microsoft this is true at least for Windows 10. There have been two studies last year, one by the Dutch government and one by the German Federal Office For Information Security about Windows 10. The latter was called Sisyphus, IIRC. They revealed that Microsoft can request e.g. a complete memory dump from your system and Windows will happily send it across the wire. And chances are, you have your private keys in memory for a while, so...
I think a lot of the original bitcoin adopters were Linux users. The giant wave of speculators that came when the price started to rise are the ones likely using Windows. I am actually more surprised the open source community has not embraced cryptocurrency as an open source money system.
It is a fact. All deflatory currencies have failed. No one is going to use their money if it keeps appreciating in value since your money is worth more tomorrow and it is going to buy you more tomorrow.
Debatable, but you do prove my point. Many in the open source community are against cryptocurrencies no matter what even though the are open networks and FOSS code. Any details you argue here can be changed with a new cryptocurrency but I am sure you have an opinion you won't change.
The issue IMO is that a currency has little value if it isn't able to be easily used for goods and services. So a small group such as open source enthusiasts would basically just trade it amongst themselves but at that point it is kind of less a currency and more of a play thing then a currency