Multisig questions

I'm thinking about creating a 2 of 2 (2 separate vendors) multisig wallet just for myself. This to simply avoid a 1 point of failure system (someone gaining access to a pin / vendor malice / supply chain attack).

1.) Must I use Electrum/Unchained/Casa/Sparrow (or whatever) to put the Xpub's in order to create the wallet? It seems I can't just create it on one of my hardware wallets/suites.

2.) If I already have 2 watch only wallets in Electrum, can I just use those xpubs to create the new multisig since I already have that info securely stored / backed up? If so that should make the transition pretty easy. I'd just have to sign outgoing transactions with both wallets that I'm already used to using.

3.) When a multisig wallet is created, does it have an entirely new xpub, and is this where the receive addresses are derived from?

4.) I see many people suggest 2 of 3 (as opposed to 2 of 2). In my case, I don't see an advantage. It seems that would be more of an advantage if multiple people had access to the account. Am I missing something?

Thanks in advance for your help/answers!