Well, all I learned from that is not to cheat on anybody, and that being "lustful" (trying to get it all the time) is bad. No where does it say "Masturbating is bad and should not be done" It just says that we should not do that all the time, or on purpose. Getting aroused sometimes isnt your fault, just hormones. So I think masturbation is A-OK.
The Bible was written by John and God told him what to write. It is not imperfect. It is written correctly, but the translations might just be off a little.