I keep my coins on my vanity address created by vanitygen
Use the public key (address) to check coins received on any web explorer.
If need to make a payment I use electrum.
Transfer the coins to the address i am making payment to and the remaining coins to a new vanitygen address.
Did you use an online vanitygen? I wouldn't trust that as far as I could throw it!
I use Electrum and the seeds are my form of 'back up'
Trezors sounds good, but I fear that a hardware glitch could lose my coins. I have heard that they are still recoverable in this case, but if that is the case, it means that the Trezor icn't really that secure anyway!
Don't click on links, use strong and unique passwords, keep your antiviruses upto date.
Your assumption isn't correct. If a hardware error should appear or you lose your Trezor, you can use the hand written seed and recover the coins just the same as you could with any other wallet using seeds. Just don't ever lose your seed and or destroy/lose your Trezor. Furthermore, Trezor is compatible with electrum and you could recover it by using another Trezor. But hey, no hardware issues for the past two years here.