Views and contextual filter as user id from url
Create a new Views view with Format, Fields, and Filter criteria configured as needed.

Then do the following:


Under Advanced, add a new Contextual filter for Content:
Author uid.
Choose Provide default value and select User ID
from URL.
Under Page settings, set Path to user/%/myview.


Now when you navigate to user/1/myview you should see content from user 1.

For Flags you need to add a relationship for the flag and filter by it. I believe this answer would help with that.