For the first few questions, they kind of answered it, they said his ramen tasted better after his trip, which is when he got the pouch and acquired the seasoning. That means he was making the ramen using substitute ingredients, which they showed him selecting through trial and error.
For the getting a building and carts. That's just background government form filling so they probably cut it out to save money. But we know they used the money from the first mission he helped with and he chose the location based on his knowledge of the Novel.
As for the last 2, they may bring up the nightmare world later and they will probably reveal mcs reasons for keeping his transmigration a secret. They could also not be asking because he has already refused to answer in the beginning several times.
Spoilers
I like this story. my only complaint is that I have a lot of questions and no answers. Like, how did he get the ingredients (before the pouch)? How did they decide to build a restaurant and how did the process even go? How did they get the restaurant? How did the get the cooking equipment? Didn’t luche and garf saw his world when they went into his nightmare, why haven’t they question it? When did they get carts to do their delivery service? Why is he keeping it a secret that he isn’t from there? Uhh I got so many questions. Also, it feels rushed.