Questions about anonymity on lemmy.world servers

I'm trying to understand how safe it is to use an account on lemmy.world to post dissenting opinions regarding the U.S. government. I have three questions:

1. If a subpoena is issued for IP records for a user or their comments, will all historical IP data be available to provide?
2. Is there a time limit on how long IP records are kept?
3. When a user deletes their account on lemmy.world, are their comments and/or IP records also deleted?

Asking for a friend...