Hi and welcome to the board. I am glad you joined us here.
I will take a stab at your questions. This is the way I understand it.
In the time of Moses, when the 10 commandments were given, there was a whole range of "gods" that were worshiped by many different people. Zeus, Apollo, Aphrodite, Baal, and so, so many more. These were established religions. They had temples, traditions, holidays, cites and so much more. They were the established gods. The first commandments says not to worship these gods. Not to put them in front of the true God of creation and of all that is.
Don't adopt any of the other "established" religions.
Commandment 2 seems to take up where commandment 1 leave off. God seems to be saying. Don't adopt any of these "established" false religions
and don't go making any new ones of your own. That was a common practice too. If you didn't have a religion, you kind of invented one. The Israelites did it when they made the golden calf and started worshiping it. People would make idols out of wood, gold, what ever they had. They would be in the shape of birds, animals, fish, people, trees, what ever they wanted. For us today we can often make, money, jobs, cars or anything else that we think will save/take care of us as our "gods".
The "WE" question is a perplexing one. I have heard it explained about the trinity of God. Father, Son and Holy Ghost.
When God says "let US create man in OUR image" Who is he talking to? Christ is, will and always has been with God.
I would love to hear other people's understanding of this too.
Hope this helped some.

Mattiez