1. I read that never store all your coins in one wallet. So wts the solution? should I install two electrum standalone wallets and store my coins in both of them?
If you have downloaded software from
original website and if you
verified signature then you don't need to create two wallet unless you lost your current wallet. But you should be careful during uses. If you aren't careful enough then even install TEN wallet wouldn't help your to prevent your fund from hackers. Your machine system should be safe from virus and malware. If you have huge amount of bitcoin then I will prefer to use Ledger nano hardware wallet. So you will be safe zone.
2. I have written seed on a paper to recover my BTC in case my computer got corrupt. What thing apart from seed should I backup to recover my wallet in case my system is corrupted.
Seed itself is enough to recover your wallet. But make sure your seed has written on multiple paper and save it on multiple places as well. So even one written seed burned or destroyed then you will able to recover it from another paper. Do not save your seed any online machine.
3. Strong password is good enough to secure a wallet or I have to do something else also.
Password will encrypted your wallet file, nothing else. If your device become compromised and hack your clipboard then likely password wouldn't help you. When you will recover by using seed then you have to setup a new password. Perhaps you would use
TrustedCoin 2FA for an extra layer security if you have doubts that you are in risk of wallet compromise.
Important: If you see any popups regarding update of your electrum then make sure its redirecting to
original website. I will prefer do not update from popups, so many users hacked by this way. Just go official website and install latest version from there. Install new version will never effect your old wallet file. So you don't need to worry about your funds.