I was a little bit fast when I tried to answer your questions.
1. Yes, I find Pocketbook 622 to be very reliable. Have never had any problems with it and it can open almost any file.
2. Have never contacted the support, but it is made in Ukraine so I would contact the seller Green reader in England if I would have any problems.
3. I find the Pocketbook 622 to be a bit slow. Specially when you reflow text in PDF:s. For Epub that I use most that is not a problem. To use the internet it feels like using an old mac from the 80's. Would not recommend it and the most pages doesn't work so well either. Get another kind of device if that is important.
4. I find it easy to use. You have 4 buttons, one home, one back, ome forwars and one for meny. Then it is a touchscreen so you just click on the screen what you would open. The only thing I haven't figured out is how you install new fonts and to get to use them in the books.
5. In the latest firmware update they added support for english to swedish. They have the menues in norweigan and finnish, but not in Swedish. But they are avaible in portuguese.
6. Yes you have buttons to turn page but can also use the screen.