If you have an album of original songs you have 2 things to protect by copyright.
1. Copyright on the songs themselves. Since they are on one album, you could do a compilation of them all for one low fee..... but if they are to be released commercially, you really should do individual copyright on each song. Individual copyright costs more but it affords the protection to one song apart from the others so each has it's own umbrella of protection under law. Look at your old albums and CD's where a band or even one person in the band is the writer of the songs. You will see that they are all individual copyrights. I can not think of one instance where a band album is protected by a compilation copyright. It's that way for a specific legal reason. Writers often use compilation copyright to protect a batch of songs but when one gets cut by an artist, it is registered with a new individual copyright.
2. copyright the physical CD so it has protection from illegal duplication.
These are protections for the "law abiding" people...... the criminals will still bootleg the CD if it's worth their time to do it. But at least you have the legal standing to sue them in court.
Copyright law is it's own unique practice of law.... a very specialized area..... Certainly if you go to the effort and expense to release a CD you should spend the money for copyrights.