When you make use of a private key you are simply restoring the wallet from a paper wallet the reason is simple, for you to be able to spend the coins in a wallet or sweep a wallet, the transaction has to be signed with the private keys, else there won't be a transaction id to broadcast to the network.
Do I have to manually broadcast something? (I watched a video where it says so)
As of now, the transaction is just sitting there with 0 confirmations after 2+ hours.
I think I messed up the fee as I just applied the default fee that was set by Electrum and it was too low so now I'm stuck for hours (maybe even days?)...