What do I need to do to start my own music label?

More than anything else, you need to learn how to run a business successfully. Take some basic business classes, talk to any local entity that supports start-up businesses, contact SCORE or a similar organization for a mentor, check out books about starting a business from the library, see if a local college or university has any programs to support entreprenours, and find someone who is doing what you want to do and ask them for advice.

You have a lot of important questions. Unfortunately, short of writing an entire book, they cannot be easily answered on a forum. I suggest that you contact an attorney for a consultation.

I help new record labels get started. You need to work closely with a lawyer on this. If you want to register a trademark, you need a lawyer to do that for you. You should register copyright on all your compositions as well as on all your completed sound recordings. Those are filed with the U.S. Copyright office. If you don't file them, you can't use the protections of the Copyright law. If you decide to set yourself up as a publisher, that is a set of work in itself, and you really need to work closely with someone and learn what you are doing. If you want to sell instrumentals, you should get licensing agreements written by a lawyer. Some people doing this run their own websites that have auto-downloads after payment. That seems to work well. The payment includes the contract for the terms of use of the music. If you are using anyone else's compositions, you need licensing for that. All in all, you need a good indie music lawyer. If you are good making music, you should hire someone to do the legal and business work for you.

You have a lot of good questions here, but they require an in depth response. All of these questions and more should be answered before you start doing business. I suggest that you contact a qualified entertainment attorney for a consultation.