There are a few guys who have done similar things on youtube if you want to have a look. It is no small undertaking though.
It is possible.
Would take several days, and might take days longer than planned if weather is bad. If the weather is really bad you might end up pushing the flight forward for weeks.
Depends on what you fly, but most have a range of a few hours. I have not done any actual checking but I would guess you should count on stops on Greenland, Iceland, UK (probably two stops) and then another few stops in west/central europe.
Yes you need to have visa (or other appropriate document depending on your nationality and circumstances) and passport and clear immigration and customs (you really didn't think there is no border check just because you don't arrive on a commercial flight? Right?).
As a start maybe look at this trip?