Maybe an easy question but important on ETH and Layer 2

[BiTCorion]

Hi
I'm new to the forum and I hope to learn a lot 🙂 In fact, I would like to ask the more experienced people here a question or advice on how to move with the entire ETH ecosystem.
The news of the ETH update which significantly lowers the fees on the various L2s has just come out so I was wondering if the time has come to take advantage of this.

I'll explain what I mean and the situation:
- let's assume that I have ETH, some other tokens and also USDC all on the ETH network (perhaps on the ledger or metamask connected to the ledger)
- let's assume that in the future I wanted to sell ETH for USDC/USDT or vice versa
Is it better to pass everything on a L2 like Optimism, Arbitrum? Better another L2? and if so, which one and how do I do it safely (considering all the various exploits on bridges and more, I wouldn't want to risk more than the usual)?
And once you get to L2, which DEX to use that takes advantage of this L2?

Another related situation:
- let's assume that I liquid stake ETH on LIDO and therefore obtain stETH as a token on the ETH network
I can also bring this new token to a L2, right? but how does it work regarding rewards? Will I continue to receive them? on which network? is it worth it?

Perhaps very basic but very important questions for everyone to have a general picture of the enormous potential of the Etherium ecosystem.
I thank everyone for their help in unraveling these doubts of mine.