1: It’s okay if you lose the envelope. It won’t affect the trademark application and you can still put “TM” on the trademark. Even if you lose the acceptance notice, it’s okay. All trademarks submitted for registration by the Trademark Office are kept on file. Yes, and your trademark information can also be found on the trademark website.

2: To prove that you registered earlier than others, just go to the trademark website

and enter your trademark application number. Just check the application date to find out.