1. Can I use one paid subscription on different windows devices?
If I pay for a subscription, will it be available on only one device or can I sign in to my account on another device if necessary?
2. Will the subscription work in Russia?
3. Is it possible to pay for a subscription with Russian bank cards?
Yes, you can use one subscription on up to 5 devices
The subscription will work in any country, including Russia
However, it's going to be difficult to pay from Russia, as Stripe, Paypal, Google Pay, and the Apple Store are blocked there. I think you would need to have a friend in a different country purchase the subscription using your email for you.