Here's mine:
1. My only rule is to switch around 6 am to avoid most of the 'missing work/school' scenarios.
2. Lots! In my current save I have played 10 households so far, but still have a lot more to go through. Singles, couples, families, some with pets, a few supernaturals, a few off-the-grid, some at uni, lots of different careers/traits/hobbies/skills/aspirations.
3. I have enjoyed rotational play for a long time, but started my current game only a short time ago as I only just started using MCCC so that they would not lose friendships whilst I played other homes.
4. Newcrest is currently my community town. It has one of each type of main community lot in it (though my other worlds do have a few community lots too). The households I play are from all of the other worlds but I guess my favourite is Windenburg because it has the island, the countryside and the town areas and it's very festive in the snow!
5. Drawbacks: If you do not use a mod in rotational play then relationship scores decrease while you are not playing previous sims and, if they drop far enough, then the relationship will be culled. I found this out the hard way after playing for weeks and then returning to earlier homes and finding they no longer had their friends. I now use MCCC solely to set the relationship decay to zero. It doesn't generally happen if you only rotate a few houses and the time gap is not large, but I wanted to do a really, really big rotation.
6. I probably enjoy families or large households most, but I like any kind of play which is why I have a big variety in my rotation.