The requirements for becoming a Certified Registered Nurse Anesthetist
(CRNA) mainly include having a bachelor's degree in nursing, or other appropriate baccalaureate degree, Registered Nurse licensure, a minimum of 1 year acute care experience (ICU, ER for example), and the successful completion of both an accredited nurse anesthesia educational program and the certification examination. This came directly from the AANA website, so you can't get any more reliable than that.
Each CRNA program may vary in length of time, but it will be roughly two to three years. It is not encouraged that you work during this time, because you will be doing about 60 to 80 hours a week of school and clinical, and that is not including homework, or study time. Additionally, most CRNA schools are very competitive and you will need a minimum of a 3.5 GPA or higher to even be considered. Some schools this requirement may be lower, but you will be going against many people with 4.0 GPA's.
To be a midwife you have to have a masters in that specialty. A midwife is a specialty just like CRNA, so you wouldn't be able to work in that capacity unless you have that degree and certification first.
As far as hours are concerned that also varies. In many cases you will have to work long hours, and you will have to be oncall. When oncall you will basically be living at the hospital. There is a reason why CRNA's get paid a lot of money. They basically have no life while in school, and that continues when they start working too.
I hope that helps. If you would like more info you can go directly to the AANA website. There you will be able to find anything you want to know about being and becoming a CRNA. : )