[Ethereum] Does coinbase charge for gas fees

In your case, both elementIndex and returnAllElements functions will cost no gas as both the functions are reading state variables from the blockchain and give an intended result.

You can optimize the above functions to reduce a time taken by them.

Refer the following question to understand View/Pure Gas usage - Cost gas if called internally by another function?

Refer the following blog to understand the difference between calls and transactions in ethereum -

https://blog.b9lab.com/calls-vs-transactions-in-ethereum-smart-contracts-62d6b17d0bc2

• How can I minimize the gas fees when using metamask?

It is possible to set custom gas fees when sending a transaction with Metamask (see here : https://metamask.zendesk.com/hc/en-us/articles/360015488771-How-to-Adjust-Gas-Price-and-Gas-Limit-). The Ethereum network is currently overloaded and the consequence is a higher gas cost. You can see the average gas price here : https://ethgasstation.info/.

• And is it true that if I set the gas fee too low, I would lose my ETH on a failed USDC transaction?

No, your transaction, in the worst case, will not be mined and get stucked. In this situation you have to send a new transaction with the same nonce and a significantly higher gas price (or just wait). Metamask does it for you with the "Speed Up" option. Note that you can't lose funds involved in a failed transaction as the transaction will be reverted by the network. However you will lose the gas paid to process the transaction.

• How come nothing was revamped to foresee a potential gas fee issue all these years on layer 1? What solutions are there for layer 1?

Gas fees are a real challenge and some solutions are under reviewed for the Ethereum 1.0 chain. One of them is the EIP-1559. This EIP has the objective to change the transaction pricing model by implementing a base fee per gas managed by the network. For more informations you can check the github page : https://github.com/ethereum/EIPs/blob/master/EIPS/eip-1559.md. Other solutions include sidechains which are a "layer 2" scaling solution enabling to lighten the main network.