@Tran3 ,I'm also at home in both camps, being a host as well as guest. I cannot answer your specific question about "Can you share stories when a preset rule helped you when problem arose?", simply because I never had a major problem with any of my guests. I attribute that to having a very clear listing, clear house rules, exchanging a few messages with my guests before arrival, as well as personally checking in every guest : all pre-emptive measures, and it works very well for me.
Like you, I believe in clear rules, but not too many. Some of the pointers, like where to leave towels, what to do with laundry, etc. I don't put that into my house rules but communicate that in person when guiding guests through the apartment and/or leaving up friendly notes about it, thinking that guests want to relax, not go back online to check my house rules point by point before leaving, but those are things I wouldn't get upset about if not followed, they are just curtesy requests, while the ones that really matter, absolutely belong into the house rules.
Just want to clarify one thing, as you say that you will charge $100 for a lost key and that it will come out of the security deposit: As hosts we don't have direct access to the security deposit, Airbnb does, so when there is an issue, the host cannot just decide to charge it to the security deposit, it has to go through Airbnb and ultimately they, not us hosts, will make the decision on what comes out of the security deposit.
Overall, I think the feeling of how stressful hosting can be is getting highlighted here in the forums, as mostly we have posts from hosts who are dealing with problems and then get frustrated when they can't easily reach Airbnb. I never considered hosting stressful before reading all the posts here in the forums!
so I prefer going back to that somewhat innocent stage where I consider hosting fun, do my best as a host and expect all to go smoothly. Prerequisite is to understand Airbnb rules, know how it all works, and have a well thought out listing - sure works for me! And looking at your listing, I think it works the same way for you. Your reviews are great, also accenting your personal involvement in your hosting - no doubt you'll be superhost in a few weeks!