I'll go straight to the answers:
1. Wich Hardware Wallet is more safe? I read that there COULD BE a risk that Ledger makers could have a backdoor in the device to access coins? Trezor is open source no? Is it more safe?
AFAIK, Trezor has a physicall vulnerability, so if someone has access to the device,
they could get the seed and steal the funds. I don't use a Ledger wallet, so I don't really know about any backdoors to it. Nevertheless, both HW are secure enough to be the most used around, and you can always protect your funds with a passphrase; that is, to say in
very vague terms, an extension of your seed. You can read more about it
here2. Did I understood correctly that if I want to get (claim?) my bitcoin cash from the BTC fork, before I do that, I should move my bitcoin from the paper wallet to a new wallet and claim my bcash after moving my bitcoin to the new wallet? So if the paper wallet is empty, I still can claim my bcash and bgold?
BCH, BTG, and any other forked coins (BSV for example), are
a copy of the Bitcoin blockchain at a certain point. If you had 5 BTC in a wallet before the snapshot, you'll get the equivalent airdropped (not always 1:1) ammount of that Altcoin at that moment in that address. Think of these forks as Altcoins, you can't send a DOGE transaction on the ETH network.
3.--
4.--
I'll skip these, as I lack the knowledge to answer them....
5. I just realized, question 3 is not important, if the method in question 2 is correct? So first I would send my Bitcoin from the paper wallet to the Ledger or Trezor. And then claim my Bcash/BGold in Exodus and sent Bcash/Bgold from Exodus to the Ledger or Trezor right?
That would be the reccomended order, yes. You first move your BTC, because you are going to be entering your private key into other platforms/wallets, and who knows who's looking... Then, once claimed, sweep them into your HW and you'd be done.
As a matter of fact, I'd say that Coinomi wallet is reccommended to claim forked coins, becuase it offers multi-coin support, so when you enter your private key, it should retrieve the coins on all the available forks at once. LoyceV does also offer a
service to claim these coinsEdit: Typos (lol); and I've realized that the thread from Loyce does also offer a table with the wallets in which (some) of the forks can be claimed