Hi there, welcome to our community
1. The 2 months will starts from the activation day, which is the day you start your first train journey. After purchase, you have 11 months to activate your Pass and start travelling.
2. You can make a seat reservation through our Rail Planner App, our Self Service system with your account or through train carriers directly. The options differ per country. An overview can be found here.
3. It’s not possible to get a refund after you’ve used your Pass, even if you still have travel days left. Your Pass is considered used when your first travel day has started (for a Flexi Pass), or from when your validity has started (for a Continuous Pass). Once it’s used, it’s no longer possible to get a refund.
I trust this answers your questions. Have a great day!