When I studied it in college, our textbook for studying Egyptian religion was Jan Assmann's (don't laugh) book The Search for God in Ancient Egypt. It's a bit dense and isn't exactly an overview, but rather a scholarly analysis of Ancient Egyptian religion over time.

If you want to read some good translations of the texts (and dabble in the texts of other cultures), I recommend

Pritchard, James B. Ancient Near Eastern Texts: Relating to the Old Testament. Princeton, N.J: Princeton University Press, 1969.

This book compiles a number of the religious texts in translation, from their myths and epic tales to their hymns and songs to their wisdom literature. It's a fantastic book, and I wish I owned it.

This book was written by the German Egyptologist Adolf Erman in 1907. I am not 100% sure of its accuracy, but it may be a good source to look at. Either way, it is a pretty interesting read, and includes of 130 sketches.

This website lists and links to different sacred texts of the Ancient Egyptians; one could say it is their equivalent to the Bible.