I wouldn't call it a strategy exactly as it's a bit to vague. More like a few general tips to get out of tricky situations. They are good ones though. A few things:
1: Upgrading is powerful but costly and best reserved for highly promoted units or emergencies. Dropping research to 0% and uppgrading everything in sight can save you if your caught with the pants down.
2: Will also give you the "mutual struggle" bonus.

Again, can be costly(bribing with techs).
3: Yes, just keep in mind that the anarchy can kill you if you aren't spiritual.
4: Preferably catas or other seige units for the collateral damage. Can take down most stacks fast.
5: 8 units in
every city is a bit over the top unless you have happiness issues and are running HR. Units costs upkeep after all. Just put them in the border citys/very important ones.
6: 10-20 is pretty much a stack of doom and you can send that many on the offense you're not likely to run into any trouble.

But Sending in fast pillagers is a good idea.
7: Not really an option if you're attack suddenly with force but good to keep in mind if you feel threatened.