When or how do we know when to use et or est?

With some of the pronounciation cards, I feel a bit confused. For example this one "Le son IN" the way I imagined it to be pronounced (Le son 'een') but your version sounds more like "ein" (like german). I went to see what google translate would pronounce it as and it also said it more like 'een'. I might be just listening to hard haha 😅 but I wasn't sure if that is just dialect or if there are different ways this could be said?

This is a really quick q! I was going over some of the decks again and notice in Level 07, some of these go like "Je vais au restaurant" ou "Je vais à la maison". Shows as "I go to the restaurant" or "I go to the house". Shouldn't this be "I'm going to ..[]"?

I have been studying the beginner deck but I’m a bit confused on what this “spoken” means. For example, the card shows: - Nous sommes - we are - On est - we are (spoken) When do we use these in specific scenarios and what is “spoken”?😄

Je I Tu You Il He Elle She Nous we Vous Y'all Ils They (Masculine) Elles They (Feminine) On One (Like One's says)