How to transfer BTC to Merlin chain?

Could you please explain the process of transferring BTC to the Merlin chain in a step-by-step manner? I'm particularly interested in knowing if there are any specific requirements or precautions I should take before initiating the transfer. Additionally, are there any fees associated with the transfer, and if so, how are they calculated? Lastly, how long does the transfer typically take to complete, and are there any potential delays I should be aware of?