Quite some question for a single comment 😄 ...I'll do my best to answer in the same order:

1. I don't think those are supported, but maybe I'm wrong. This is not related to PeakD itself, but to the service used to retrieve the images. I would say that it's worth a try ;)
2. Not required, but can be nice. Keep in mind that usually a very low amount is required for an average user
3. No sorry, also I'm on Linux so not sure what options are available for Windows
4. This is probably up to @jarvie
5. No, it works in the browser. Keychain on mobile is still in beta, but it should work. Otherwise you can try with Hivesigner or PeakLock
6. No, not possible at the moment