You can leave for up to 2 years. After that the permit expires.
You can stop paying the health insurance, but you have the option to pay a small annual amount which will allow you to be re-insured under your present terms and conditions.
I'm not 100% sure, but you'd only pay (the usual) tax on fixed property.
Yes, it will impact negatively on your application to be naturalised Swiss.
Re-apply for insurance is only relevant if you have more than just basic insurance.
Non-residents are not taxed. But real estate might be.
The minimum residency time in the commune/canton will reset. This period is 2 two 5 years depending on commune/canton. The federal residency time does not reset. If you have a pending naturalization application it will become void.
Whatever you are doing, if your long term plans mean living in Switzerland, then paying your state pension(s) in those absent years might be a good idea...