Thanks for highlighting your queries. Answer to question # 2 is no. It's limited to posts.
Question # 1: If you are signed up and whitelisted, you can get votes from people who only vote for whitelisted people. Without whitelisting, you will get votes from only those people who allow votes for everyone.
Basically, whitelisting matters here, not just signing up. I hope your query is clear.
Thank you. One more question:
Is value of the upvote affected by registering or not?