2011:
1/ Yes, that seems the safest approach, as any modification you end up back-porting in nicstrong/projectA will be in a project with the same structure as original-author/projectA.
That means pull requests will be easier to organize, since you will be in a project mirroring the original author’s project.
2/ If you have massive refactoring going on in nicstrong/projectA-android, I would make a backport branch, carefully merge or cherry-pick what you need from the numerous changes to the backport branch, and then push that branch to nicstrong/projectA.
(which means you have added nicstrong/projectA as a remote of nicstrong/projectA-android)
2022: Note that you can create a fork directly with a different name.