What do you think about ETH pool staking, for example in Rocket pool?

I am trying to educate myself on staking ETH, if I understand it correctly, you can stake even small amounts when you stake in pools. But I have some questions, if someone more knowledgable could help me. Sorry if any questions seems stupid, just trying to understand it properly.

1) is it safe?

2) how exactly does transfer into pool work? Do I just send ETH from my wallet to their?

3) what is the rough gain from it? Let's say I would put 0,01 ETH into it, what can I expect?

4) apparently you get some kind of token on Rocket pool which represents your stake, how does it works, is it added into your private wallet or stored somewhere in their app in your account?

5) what other staking pool would you recommend?