Away & Home buttons with Guest

Not that I'm aware of.  To clarify, do you not want them using the system at all?  If so just remove the keypad and use the app for yourself.

Some guest may want to use it, if so I'll give them a code. Just didn't know if there was a way to prevent them from turning the system on if they didn't have a code and for some reason pushed the home or away button. I thought of that also, that for ones that don't want to use the system I guess I'd just be better off to move the remote. If the system is off and you remove the remote from the house will the system show an error or notice that the remote is out of range?

It may report an error when armed or disarmed.  I know it does when batteries are low for the keypad.  The base station might generate a light indicating an error. But if the system is off it won't be repeating the error via voice or anything like that.

Is it expecting too much simply to tell them not to mess with it, as doing so probably will get them an unexpected and unwanted visit from the Police?

I'd expect that should be good enough for most other than an idiot to understand. In the case of an idiot at your rental...well, you got bigger worries than the alarm if that's the case.