There is being transparent (the fridge in this unit is likely to fail) and telling them stuff they don't need to know (you have $1M in the bank).

After they moved, in a routine clean-up, we discovered some broken refrigerator drawers that needed replacing (not really something we would see in a normal walk-through).We purchased new drawers, seeking reasonable prices because the fridge’s manufacturer had outrageous prices for the items, and we were able to save more than half of the cost used from the security deposit.So far so good.

Stock the fridge with water.Small things REALLY make the guest happy and more likely to leave a review.

As far as wifi passwords, the only place I put this is on a magnetic holder that is on the fridge.

Now we bought a new $600 fridge for the mobile home we're renting out that we paid $12,000 for. 

People sell fridges, stoves, and appliances that are in perfect condition for 1/4 the price of new and about the same cost of a typical repair bill.

. , ¾” bath is definitely a strike against it, I know 0 people who bathe, not an actual duplex, so some people may be annoyed by having to share a fridge, appliances, etc, living space in general.

I would ALWAYS suggest including the local police non emergency line, that comes in handy often and prevents unnecessary 911 calls.Even if utilities are paid by you, it's not a bad idea to include the numbers of your eclectic, gas, and water providers- even if their names aren't on accounts, they can find out when power will be restored quickly (saving you or PM a three am call maybe)As far as gifts go and actual items, things that would apply to most everyone in being useful seem like a good idea (an not offensive in any way like scented candles - those items are not across the board items) but things like nice dish towels, simple kitchen tools/gadgets, a welcome mat, fridge notepads and nice pens, etc. 

But I don’t want to just leave this fridge behind because it was way too expensive to do that.

I got them a new stainless steel fridge and dishwasher too.