You only need to backup mnemonic seed. If you backup it, you are safe.
True, but in case of a fork electrum might only work for one of the possible bitcoin forks[1].
With Electrum 1.9.8. you click Wallet -> Private Keys -> Export -> "enter password" -> OK -> "read warning" -> OK -> save
It will create an unencrypted(!) .csv file with all private keys and corresponding addresses.
[1] Add for clarity: Im referring to the possible split into two distinct coins Bitcoin and Bitcoin XT here, not a fork within the same coin.