One other question :

On the Electrum Wallet, when I open it there's the choice between opening the current standard wallet (let's call it "wallet_a") and a password is needed or "Alternatively" Create a new wallet.

-If I Choose the option "Create New Wallet" (let's call wallet_b)
-When the dialog box asks "What kind of wallet do you want to create ? " --> I have to choose "Import bitcoin addresses or Private keys"
-Enter the private key of the "Cascasius" coin in the dialog box and click on "Next"
-After that, my Electrum wallet (the new one then) should show exactly 1.BTC as balance and I will have the possibility to send the amount on the exchange platform of my choice

However, what I think strange is :
-For opening the standard wallet already created I need a password
-When I create a new wallet (for importing the key) they don't ask me for a password for the new wallet. Is it normal ?

Therefore :
-How do I find the wallet_b (the one created by "importing private key" in case I close Electrum. I ask that because they don't ask for password
-I want to be sure when I click on "Import private key" that there is access to a new wallet with the possibility to "Send" to an Exchange

Sorry if it seems stupid but the absence of password for the new wallet when import keys worries me a bit.

Thanks for your answers.