Noah, the sloth, seems to have just been given a random name, but in the original series. The humans left Earth in fear of the Scub. When they returned thousands of years later, they found they could live on the planet again. This is somewhat similar to the Biblical story of Noah, so the name serves as a Call Back.
Quartz is used to make watches in real life. Quartz, in the show, enables time travel and can alter history.
If Ao does in fact have an older sister, then it means Eureka and Renton have two biological children and three adopted children (they presumably still exist). In other words, Ao and Eureka are part of a family of seven.
Translation Convention is fine, but that dosen't explain how everyone from the multi-national Generation Bleu can understand each other. Either everyone speaking some common language (probably English), or there are Translator Microbes. Then again, they do have a working AI in this setting, so auto-translation devices wouldn't be that farfetched.