Thank you!
Yes
If you divorce in switzerland sure, but if one or both of you move abroad, there will be a question (or even choice) of jurisdiction to divorce in and it can get pretty complicated. Divorce laws are hairy in a lot of countries, there's no 100% guarantee your new jurisdiction won't just toss away your prenup.
I don't believe there's any such restrictions in ZGB. But it should be a language that both you and the notary are able to converse in (or else you're going to foot the bill(s) for translators when signing it and during any disputes from it). English is probably a fairly safe bet.
btw a swiss lawyer told me that pre-nups are a nightmare because no matter what good intentions go into setting them up, they're often contested later on, usually by one party saying they 'didn't understand' or were 'coerced'
The inventory is to be complete and covers worldwide assets.
The governing law (also see the link) is national (aka "federal"), so little to no change by changing the location within Switzerland.
As for suggestions, just search for notaries by municipality or canton.
Inheritance law shouldn't affect you WRT the marriage if you have separation of goods. But if you have close relatives (children, siblings, parents, grandparents) you probably want to check on that as well as AFAIK the place of death generally determines the governing law, and Swiss law rules that close relatives have mandatory minimum shares the lessor can't reduce (those shares are bound to change in the coming years as the law is being revised), that reduces the lessor's flexibility by quite a bit.
Yes, there are certain things prescribed by the laws that you can't get rid of just so by signing a piece of paper - like compulsory inheritance portions that you mention, or child support, etc. Any lawyer worth their money and I believe notary itself too will advise you if you put something obviously unenforceable like that into your prenup/will.
But there are still good benefits to be had from using prenup/will. Like establishing Gütertrennung (separation of assets/income) property regime vs. the default Errungenschaftsbeteiligung (communal property) requires signing a marriage contract.