Where to get Personal security key, which will help me if I loose my 2Key related app?
It depends of your wallet. If you downloaded the QT, go to help-about-debug-console and write dumprivkey. Another option is to save your wallet.dat . This is only about backups.
If your using wallets like electrum or multibit we're just changing the story right now.
If you're using an online service is good to use 2fa as you asked in the OP.