Yes, of course, you can. In a transaction of Ethereum, you can find there a private with a signed message from the actual owner. Look at the transaction hash, find out the 64 characters long string that are 32 bytes that are a public key and that is different from Ethereum address which is 40 characters or 20 bytes. But as far as I know that the difference between the private key and the public key is a private key can create a signature and public key verifies the signature.
Yes, correct. The private key is 256bit number and used for signing, and the public key is 512bit number (actually 2 concatenated 256bit numbers) and used for veryfying.I can't explain more because I'm not kinda experts about Ethereum transaction but I have found a medium post that related to your question, Here.
I think this is the answer, thank you. As I understood there are no public keys in ethereum network (like in bitcoin for example), but it is possible to retrieve the public key from the raw signed transaction (with the help of a separate script of course).
