Getting in/out and around Okinawa

Ive booked a hotel in Okinawa city for five days. My plan is to island hop. Does anyone know if this is as easy as Im hoping?
Also, what is the best route to get into Okinawa? Fly? Ferry? Ive purchased a JP rail so I need some inexpensive options if possible.
So far my itinerary is Tokyo--Takayama--Kyoto--Hiroshima--Okinawa.
How many days will I need from Hiroshima?
I know this is Lengthy! Any guidance is greatly appreciated.

Does anyone know if this is as easy as Im hoping?

Depends on the islands you intend to visit. Yes, it its the ones close to Okinawa main island. But the other big islands are further away and are best reached by plane.

Also, what is the best route to get into Okinawa?

You pretty much have to fly. Flights can be really cheap if you go with an LLC like Jetstar.

So far my itinerary is Tokyo--Takayama--Kyoto--Hiroshima--Okinawa.
How many days will I need from Hiroshima?

To reach Okinawa? It's about a 2 hour flight from Hiroshima Airport, but if you can get discounted tickets and have a JR pass you might want to consider rearranging your schedule to fly from Kansai Airport instead.

Hello! :)

If you're staying in Naha City, then you could do day trips to the Kerama Islands:
http://zoomingjapan.com/travel/kerama-islands/

For islands hopping I recommend the Yaeyama Islands, but it doesn't sound like you'd have enough time for that:
http://zoomingjapan.com/travel/yaeyama-islands/

I would say 2 days are enough for Hiroshima (1 day for Hiroshima, 1 day for Miyajima) unless you're also interested in visiting "Rabbit Island" (then +1 day):
http://zoomingjapan.com/travel/rabbit-island-japan/

from Hiroshima take the shinkansen to Hakata/Fukuoka and a Peach Air flight to Okinawa.