Hi Vikesh, the nearest airport to Auli is Jolly Grant Airport in Dehradun (279km). Nearest train stations are Rishikesh, Haridwar and Dehradun. You can take a private taxi, shared taxi or state buses from these places to Auli. Some of the top Auli attractions are - Auli Artificial Lake, Auli Ropeway, Gurso Bugyal and Chattrakund. There are limited accommodation options in Auli. But, Joshimath has plenty of options. You can take the ropeway from Joshimath to Auli. There are restaurants in both Auli and Joshimath. Let me know if you need any more information.
Hey Vikesh, Co-incidentally just yesterday i have written my first travel blog on tripoto and its on Auli. Just have a look at it and you will get all your answers. For any other query you can directly ping me.