Koyasan to Shimoda and taiko festival?

3 people are travelling during Obon (Aug 9-17) week to Tokyo, Osaka/Kyoto/Nara, Koyasan, Shimoda and the Izu islands before heading back home to Yamaguchi.

Not sure of the order yet, but there is an Obon festival in Koyasan on the August 13th and a taiko festival in Shimoda on the 14th and 15th.

Any advice on how to get to Shimoda from Koyasan, and further how to get to Shikinejima? Would it be beter to go back to Osaka first, spend another day there before heading over to Shimoda on the 15th?

And does anyone know at what time of day the Shimoda Taiko festival takes place?

Last question: Any good route from Shimoda to Yamaguchi? Or should we spend another day in Kyoto area on the way back?

Any advice on how to get to Shimoda from Koyasan

By train via Osaka and Atami:
http://www.japan-guide.com/e/e6305.html?aFROM=2157_6310

and further how to get to Shikinejima?

There is a ferry from Shimoda:
http://www.tokaikisen.co.jp/

Any good route from Shimoda to Yamaguchi?

By train via Atami. It is about a 7-8 hour journey.