Private Key leakage due to reusing same address, how to prevent? 1 What precisely is the meaning of &quot;reusing&quot;? Is it receiving multiple times coins to the same btc address? Or is it also about sending coins?
2 How can people avoid this leaking of information when using a wallet, best practices?
3 How many times of reusing could be enough to seriously allow leakage/reingeneering of the key? Just one time is enough ? Possible to make any estimations?
4 Is this reusing problem only inherent to bitcoin? Or which other blockchains would you know of with same issues?
No, reusing address won't succeed in private key leakage (assuming quantum resistance).

Yeah, reusing has two meanings - if you use static address it may succeed in lack of privacy. Imagining the situation when you share single address with police department for some contract work, and also you use the same address in your darknet market store (hypothetically).
But reusing is also related to spending from an address, during which you share your public key (it's needed to be shared publicly to confirm transaction signature).

Use BIP44 scheme, don't share one address to more than one person. Use invoices (btcpay server) rather than static addresses. If you want to be even more private, use P2E or Paynym's protocol.

As in example in point 1, once is enough in some case

Address reusal is a problem in utxo-based blockchains. Ethereum, being account-based is much less affected by it, as the privacy on this front is non-existent by default in account-based model blockchains. With bitcoin, utxo model is at least preventing users from obvious mistakes.