Can you share some more details?
A key feature of decentralization is that blockchain transactions are irreversible by the sender. So, if you want a refund, you will have to get the person controlling the transfer recipient address to transfer it back. If no one controls the address, unfortunately there is no way to retrieve the funds.
This is the case (unfortunately), when someone transfers RSK tokens to an Ethereum, or other network, address. By design, blockchain transactions are irreversible by the sender. You will need to speak to the exchange.
No, this is not possible. An RSK address is required to send or receive RBTC. If you wish to convert between BTC and RBTC, you may consider the RSK PowPeg.
No, this is not possible. An Bitcoin address is required to send or receive BTC. If you wish to convert between BTC and RBTC, you may consider the RSK PowPeg.