You have to pull out a Pressure cleaner if you want to swim in peace. Personally, I don't like swimming around and avoiding any cleaner. That said, I have been in the pool many times with the Dolphin running, but if you are worried about it from a safety standpoint, just unplug it.
As to your other questions, yes to all of them. Until the new wears off, you'll find yourself watching him at work though. I suggest the Z5 or the M5, but these are the two I have personal experience with. Whatever you decide, don't skimp on price. $$$=Cleaning power.
Does it do well with leaves?
If I go on a business trip can my wife leave it in the pool until I get home in a week or two?
Does the Z5 have a timer? For example I can set him to run an hour a day? I guess I could put in a normal plug timer. I am thinking of leaving it in the pool until we want to swim and pull it out. Or should it just be ran and removed when not in use? Would that effect the longevity of the robot?
What is different about the m5 to stop it from getting stuck? Does it sit higher off the ground?
center brush prevents it from getting high-Centered...
I have never had any issue with my Z5 getting stuck on my drain covers. It drives right over them. they stick up....I haven't measured how much. but they are pictured in more than one spot on this forum.