1) If I read correctly, RBF is an option I can activate for future transactions? I will definitely look into this and making sure I have a high enough fee for any of my future transactions. I work with Electrum, not with Mycelium. When I right-click on the unconfirmed transaction, I don't see the 'selecting increase fee' option.
Yup. You can't increase the fees on the transactions that you have already broadcasted. If you have the replace by fee option selected, you can create another transaction with a much higher fee to "replace" the current transaction that is in the mempool.
2) I am the receiver of the funds, but on the Kraken account. When I right click on the unconfirmed transaction in Electrum, I do see the 'Child Pays For Parent' option, though. Should I try this out?
Sure. Child pay for parents allows for child transaction (the transaction you are creating) to help to incentivise the miners to get the whole chain of transaction confirmed. This method will work as long as the transaction has an output to an address that you control. This does include a hefty fee however, since you are also effectively creating a new transaction.
So for the CPFP option, could I assume the fee gets doubled? Or what would be an effective fee to unstuck the transaction?
Edit: To clarify, I mean to ask if a sufficient fee would get doubled. Not the original fee.