Need help with first time French Polynesia visit :-)

Hello folks,

As part of our worldtrip we (2 person) are stopping in French Polynesia for 27 days (24th April to 20th May). We know it is a very expensive destination, but as it is “on the way” we decided to stop there. We are planning with a budget of 65€ per day per person including accommodation, food, tours and transportation within the islands itself. We are planning additional 600€ for transportation in between the islands. Not sure yet either we should try to go by boats (would be probably much cheaper than 600€) or buy an Airpass. My girlfriend is under 25. In the Lonely Planet it is mentioned that there is 50% discount for people under 25. Is that still up to date? We could not find any information about that on the Air Tahiti Homepage.

We are wondering now which islands we should visit in this short period of time as there are hundreds of them. We definitely would love to visit an Atoll as we never have been to one.
Our idea so far is visiting Moorea, Huahine, Maupiti, Fakarava and Rangiroa.

1.) Do you think the budget we calculated will be ok? If it is way to less, we would have to consider to stay just on the society islands and so save money on interisland transportation.
2.) Is this maybe already too much/too many islands for 27 days? If yes which island(s) would you skip?
3.) Would you recommend not to go to one of these islands and to visit Raiatea instead?

4.) Would you recommend spending some days in the interior of Tahiti or better using the days to spend some more time on the islands mentioned above?
5.) Do you have a recommendation for some good places where we could do some beautiful hikes without a guide as a guide might be too much for our budget?
6.) Would you recommend to visit both atolls (Fakarava and Rangiroa) or are they so similar that we should visit just one of them?
7.) We are planning to put up our hammock or tent on some secluded beaches and sleep there for a few nights for a great experience and also for saving some money. Is this easily possible in French Polynesia?
8.) Do you think the period of time we are going to visit French Polynesia is still Low season and we can bargain the prices a bit down?

Thank you very much for your help!

Happy travels :-)
Boris