[Ethereum] Dynamic total supply for ERC20 tokens

For question 1 I think you're point about the scale being important is correct, buying something with 10 tokens instead of .0000001 or 1000000 tokens. You should come up with a best estimate of the range you expect the market cap to be and have the supply be within an order of magnitude of that so the range of normal amounts is what most people are used to dealing with.

As for minting/burning, this is dependent specifically on the project. MKR for example is minted only in the case of under-collateralization in an effort to pay off debt via inflation, and it's burned whenever someone uses it to pay off debt. Many tokens just don't have any minting or burning. It completely depends on how the economics are supposed to work.

Basically correct, but you need to set initial balance for owner also and from the beginning, the balance of owner equal to total supply. Total supply is nothing if you dont handle the token balance for each account/address in your smart contract.

for more detail, you can refer to openzeppelin template code

https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/contracts/token/ERC20/StandardToken.sol