The YouTube Community has flagged

Your account has received one Community Guidelines warning strike, which will expire in six months. Additional violations may result in the temporary disabling of your ability to post content to YouTube and/or the permanent termination of your account.
For more information on YouTube's Community Guidelines and how they are enforced, please visit the help center.
Please note that deleting this video will not resolve the strike on your account. For more information about how to appeal a strike, please visit this page in the help center. 

Let's see I know nothing about youtube content laws but I'll give it a shot.
1) If you get another one after that period they'll reinstate the 6 month warning strike again but the first one already expired so it won't be held against you.
2) They'll most likely disable your posting abilities or terminate your account entirely as they said.
3) Yes it'll go back to normal
4) It says it'll expire in 6 months so I'm guessing if you're missing posting abilities such as custom thumbnails they'll be back after 6 months.
DO NOT ADVOCATE THEPIRATEBAY ON ANYTHING, IT'S A SENSITIVE ISSUE EVERYWHERE ESPECIALLY YOUTUBE