I can’t help you with the chair other than to advise going out and sitting in a few until you find one you like, but I can suggest getting a silicon wrist rest [1]. I spend most of my time typing (only 8 to 10 hours) and I find they really help me avoid neck and shoulder pain.
I understand this completely - I'm in Norway. Sometimes the choice isn't there.
I don't actaully have chair suggestions - I think the actual choice is personal. I have a preference for more of a lounge chair for my computer desk because a good one has back and neck support as well as the room to adjust and sit comfortably, even if that means I'm in lotus position on my chair. Not only that, but it seems more likely that you'll be able to test the chair first. I suppose that many people would miss the wheels, but if you can find one that swivels, the wheels don't seem to matter as much. You might be able to install casters (didn't see those in stock at Ikea, but the hardware store had plenty).
I do have suggestions that might help you until you find 'perfection'. Back in the states, I remember seeing lumbar support cushions. Something like this might just make your current chair bearable or at least buy time - and you can use that general shape to help guide your next chair. It is possible you can make one as well. You might try adjusting the height of your screen if your neck is hurting (even if this wasn't an issue before).
I would love to try a lot of chairs, sadly there is limited places where I can (and they do not really have a lot to try).
It's just so I have some brands to maybe look into further before going out to try (if I can find them).
Thanks!