No issues.
The routers are not region locked, and when setting it up you are prompted to select a country/region. Doing it, selects the correct frequency for tour country.
(Correct frequency means set by your government)
I moved a lot between countries and always left my router set as north America, never had an issue with it.
Most probably not.
Those are for printers.
Also you need to set it up in the router software