3 of them will be from South America, that was the deal, nobody knows the rest because we don't know which team will qualify but the obvious chance is that the other 3 will be from outside, they will probably try to force the odds so it will be Europeans ones in order to avoid making a team travel to 3 continents.
Depends a bit on what the distance really is, for example, between Madrid and Lisbon you have 600 kilometers, and this is between two countries, for example, fans trying to get to Lille from Marseille have around 1000km in the same league Normally top teams get at least 30% of the tickets, spread this across 20,000 fans and if we count richer countries I assume it would be easy 5k fans that would travel across these countries to see all the matches.