Wow, some people really aren't getting this show. I just saw a review with a list of supposed "unresolved" questions, that just demonstrated the poster's inability to watch and understand the show.
Firstly, it's clear that the silo dwellers did not invent the technology they use - that was all invented by the people who built the silo, and that information was lost in the mists of time and due to the rebellion where most records were lost. The silo dwellers can use/fix what they do have simply by passing on that knowledge from generation to generation, but they don't have all of the scientific knowledge that allowed it to be built in the first place.
For the other questions:
1. The records and relics that were destroyed didn't mean that they understood all of that stuff, it just meant that they had records. They still weren't the people who built the silo. We don't know how long ago it was built, but it's clear it was a lot longer ago than 140 years.
2. There is more than one cafeteria. This is made clear because the mechanics had their party in a cafeteria when Cooper (?) was made Juliet's shadow. Did you think they all trooped up 130 levels to attend it? No, there are numerous cafeterias, each with a camera view of the outside.
3. They grow their food, they likely recycle their water. How the generator is fuelled is revealed in a later episode. Are you really so incapable of patience that you're upset that not everything is explained to you in the first episode?
4. Again, they keep the machines running, they don't understand the science behind them - they just understand the mechanics. Also, they don't necessarily have access to a heap of resources to make whatever they want. Also, there is clearly a huge cultural taboo on going outside.
Just watching the show would have literally answered all of your questions.