The 12 words are 128 bits of entropy, which is considered more then enough.
128 bits of entropy is very enough, with the additional of 4 more bits during checksum which makes it 134 bits before the generation of the 12 word seed phrase.
Obviously more words would make it more secure.
Yes, but also the use of passphrase can help, especially to ease mind of any uncertainty. ps1234, know that the additional of passphrase will rest to generation of different keys and addresses entirely, of you do not have the passphrase anymore, only seed phrase can no be used to receiver backup your wallet during wallet recovery.
However, it is more likely to loose money due to carelessness / not keeping good security practices then it is to loose BTC due to someone randomly generating your seed phrase.
Carelessless and hack has been the reason people are losing bitcoin.
A 12 word seed phrase generated by electrum provides 132 bits of entropy.
DaveF meant the BIP39 standard which is 128 bits of entropy. It is quite new to me that it is 134 bits on electrum, I only thought what is different about the seed phrase between Electrum and BIP39 is how they are generated and inclusion of version number for Electrum seed phrase, I do not know if the entropy is not the same.