I'd like to correct three false myths about writing songs:
1. You need to form a publishing company.
No, you don't.
You can form your own publishing company but just know that if you are signed up as writer to a performing rights organization (PRO) such as ASCAP, BMI, SESAC, SOCAN, etc, your publishing percentage will automatically be credited the same as your writer's percentage to "[Your Name] Music". That is of course unless you have signed an agreement with a music publisher who will then own all or part of your publishing for the songs under that agreement.
If you are just getting started, you will not need to set up a publishing company. Creating a publishing company will not mean that you receive more royalties. You are not leaving any royalties on the table.
2. You must copyright all songs with the US Copyright Office
Yes and no.
If you want the best legal evidence/ copyright protection for your song, yes, do the formal copyright with this office. The electronic filing of one song costs $35. You can do compilations for far less, if the songwriters and percentages are the same for all songs.
However, if you write lots of songs, you may wish to do as the major publishers do... formally copyright only the songs which are going to be cut and released for public consumption.
Your intellectual property (song) is actually considered protected as soon as there is any evidence of it (lyric sheet, worktape, email of it, demo recording). You can go further and mail a certified letter containing the lyric/worktape to yourself and never break the seal. This is known as the 'poor man's copyright'. But attorney Fred D Zemel lists 5 advantages for registering a song with US Copyright Office on Entertainment Law blog.
3. A record label can release a song from an artist and deal with paying songwriters/publishers later.
You (the label or the artist/label if you as artist own the label) are legally required to do a mechanical license BEFORE you release your project. If you're the songwriter and you find out someone has released your song without obtaining mechanical license from your publisher, your publisher can take legal action. You can usually take care of this by alerting the label/artist that this needs to be done immediately or the song needs to be taken off the market.
Hope this provides some clarity for you songwriter voices out there... comments welcome!