I don't think any horse wishes his owner dead....unless the owner is abusive or something...and then they might act to protect themselves. I've never heard that saying before, and I've never owned or known of a properly cared for and trained horse that ever tried to kill someone.
Like the others have said, if you are unfamiliar with handling horses, or don't know how horses think or react to certain things, you could potentially get hurt, but not because the horse is out to kill you on purpose.
For a first horse, I would definitely say go with a gelding, though there are some perfectly lovely mares out there. Each horse is an individual with individual personalities...just like people. If they are gentle and well trained, you should have a good horse.