Questions about ERC20 Tokens

I learn UNDERSTAND THE ERC-20 TOKEN SMART CONTRACT and I’ve a 3 questions.

1. What actions updates it? I solely see a worth set on the level of contract creation. My guess might be burn and mint actions (or are there different actions?). Which ends up in the second query
2. Why is Mint and Burn not a part of the ERC20 interface?
3. The entire provide is assigned to balances[msg.sender]. Appropriate me if I’m unsuitable, however this implies the account that deployed the contract principally owns all of the tokens initially? Is there not some safety fear right here? If the personal key’s compromised that the funds could be moved from it to every other accounts! Has there been circumstances of exploits that occurred due to this? In actual life state of affairs how do folks deal with this safety dangers? Are there a unique sort of ERC20 the place provide is unfold and held by a number of accounts?