Yes, it is. By changing the derivation path you create what is known as a new account. Ledger Live will deal with the derivation path automatically for you in the background - all you have to do is add a new account for the coin in question (bitcoin, in this case), and the address type you want to use (legacy or segwit). There are instructions on doing this here: https://support.ledger.com/hc/en-us/articles/360006410253-Add-your-accounts. The only caveat here is you can only create a new account for each address type if the previous account for that address type has received a transaction already. This is to stop users creating dozens of unnecessary accounts and then forgetting which one their bitcoin is in.

If you follow this method, it is important to remember what is happening in the background - Ledger Live is changing the derivation path for each account. This is important if you ever need to restore your seed phrase to another wallet, as by default most wallets will show the first account only, and you'll need to specifically tell them to look for other accounts.

No.
There is no link visible between single addresses generated from the same seed.

As long as you are not signing a transaction with inputs from both addresses, or are being analyzed through some meta data (e.g. using web wallet from browser X with addons y,z and a specific resolution, etc..), you are fine.




No.

Provided you do not reveal your master public key or other details of your wallet, then there is no way to link any two addresses together just by looking at the addresses. In both your questions, there is no inherent way to link addresses together, be it two addresses from the same wallet, or two addresses generated by the same seed phrase.

The most common way that people link addresses together is either by spending from two addresses in the same transaction, or by doing this via another address. For example, you have some coins on address A and address B, and you use both these addresses in one transaction. They are obviously now linked. If you later use address B and address C in the same transaction, then it is fairly trivial to also link address A with address C via address B, even though they haven't shared a transaction.

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If you want to be completely safe, then you could use derivation paths to create a whole new account. This essentially uses the same seed phrase but generates a whole different set of keys and addresses. Once you are done with wallet A and you empty it, rather than using different addresses from A and running the risk of making a mistake and accidentally linking the new addresses to the old, you can just use a different derivation path to create a brand new wallet. If you let us know which wallet we are using, we can talk you through how to do this if you like.