I have little knowledge on desktop wallets but as far as I know if I have the private key of my wallet stored somewhere safe and if someday my hard disk blows up, I can still get my wallet and full balance back with the private key, is that correct?
It is a little bit more complicated than that, but yes you are right. With electrum, rather than dealing directly with your private key, you have to
memorise a seed. Your seed is a random sequence of words that correspond to your private key. And you can write them on a piece of paper and store them securely. In case your hard drive blows up, you can install a new installation of electrum wallet on a new disk and just import your memorised seed and all your balance is under your control again.
Also can I password protect the electrum software?
Not that you can, but you
should. That brings another layer of protection to your wallet.
Nice one. Thanks for the explanation. Another fear keeps me from using desktop wallets is that I am skeptical that these apps may secretly spy on my activity and steal things on my pc. Maybe that's absurd, but who knows? Is electrum open source?