How to assemble an electrical panel for a garage and how to bring electricity to it?

As for the earth and zero - it may be necessary, it may not be necessary. You don’t say what’s happening in your introductory board, where you got your land from and what kind of grounding system is organized. If TT - then it is not necessary, if TN-C-S - then it is also not necessary if it is already connected in the shield.

If there is a shield in the house, then it’s all the same any metal, even plastic, which one you like and put it on. If metal, then its body must be grounded.

On the street you need to use metal shields.

What exactly is the right way to connect? Since this shield is additional and there is earth, I would put in your place 1 automatic machine at 25-32A and 2 difavtomats (or 2 RCDs + ordinary automatic machines - the same in meaning and functions): one of them into the light (6-10A) , and the other to the outlet (Not more than 16A). Or vice versa, 1 difavtomat common to 25-32A and 2 conventional machines

How will you connect your inverter and compressor? Are they designed to be plugged in?

What is the value of the introductory machine? Does it allow the use of a compressor and an inverter at the same time? If possible, then divide the sockets into 2 groups, i.e. put on them 2 different difavtomats at 16A, then you can load the sockets at the same time to the full, but the main thing is to know which of the sockets is connected to which group.

In some cases, they just make an automatic machine and a separate outlet for a powerful consumer, they also sell power sockets for 25-32 Amps, and even three-phase ones. In general, your question makes me more guessing at the coffee grounds than answering. If I did not answer you what you wanted to hear, then ask your question more specifically and in detail.