“Does a bible and a hymnbook have the same divine inspiration and authority”
It does if you are using a Psalter.
http://www.amazon.com/Trinity-Psalter-Psalms-Words-Only-Edition/dp/1884527078
http://www.amazon.com/The-Scottish-Psalter-Including-Paraphrases/dp/1453856242
Not any added musical notes or instructions, and not any non-biblical text.