Have new apple watch - heres my obs.

1) Make sure iphone and apple watch are up to date or they wont let you pass go.

2) Region doesnt matter - I am on UK and could still register a Suica

3) Yes for a named Suica - if you have problems with a blank suica from what I can understand theres not much they can do to help - having a named suica means you can reload the suica after phone change / reload

4) No issues with foreign card.