Slides in/out? That's your choice. It does not hurt anything to leave the slides out as far as the mechanics of the camper go. Personally, I feel better with them "in" when not in use a while, just so the roof stays cleaner (bird poo), leaves, bugs, and windy debris (tree branches falling), hail, ect possibly damaging the roof. Why risk it? But as far as the camper goes, they can stay out all the time.
Fridge: We keep our fridge on 24x7, even when parked at home. Our new Outback, we turned it off over the winter (first time we've turned the fridge off any camper in over 10 years). Does not hurt to leave them turned on. We empty our fridge, except for ice and canned soft drinks. Anything perishable goes back in the house. In the event of power failure and if the propane ran out, we don't want anything to spoil and stink up the refrigerator. But just leaving it "on" will not hurt anything.
I would definately turn the water off at the outside faucet. We do this even in campgrounds when we're going to be away from the camper for even a couple hours. The last thing you want is to come back to your camper after a week and find out you had a line inside the camper break and water's been running inside for the last 6 days! Always a good idea to turn off the water at the spigot, but no reason to drain the lines in your camper unless you're winterizing.
And yes, if you're going to be gone for a length of time, it's best to turn the water heater off. Same reason as above, the potential for a water leak is there. It only takes a few minutes to reheat water. (especially if your turn the outside spigot off).
I'd put the stinky-slinky away if I were gone a few days. You're correct, critters can damage them. Why take chances? Kids can trip over them. Vandals may damage them. It's a quick thing to do and you have peace of mind knowing they are safe-out-of-site.
There's not much you can about mice or bug infestations, except make sure every nook-and-cranny is button down tight. Look for any holes and pump them full of foamy "Stuff" or something to keep the critters out!
Keep your windows close tight and doors locked tight when not there. Don't tempt a thief.
When your gone through the week, button it down just like you would your house. Leave nothing readily available for damage or theft. It's a sad day when you have to start replacing things, and if it's a human that caused damage, such damage can make you loose faith in people real fast, and cause serious doubt about those who are parked beside you too! Button down. It's the best thing to do.
