Who wrote 'Panchtantra'?

According to Indian mythology, who among the following sang the Shiva Tandava stotra?

Which is the river that crosses the Tropic of Cancer twice?

Which state of Northeast India does not have a railroad?

Where is Dilwara Temple located?

In which century was the printing press discovered?

Where is the Central Institute of Indian Languages located?

Regud soil is the highest?