You can get to French Polynesia reasonably easily from most parts of the world. It appears inaccessible but that is simply the distances involved, and the length of the flight particularly if you are coming from Europe or the eastern Seaboard of the USA.
Airlines such Qantas, Air New Zealand, Air France, Hawaiian Air, all fly into Papeete to Faa Airport.
In terms of getting around the scattered island of French Polynesia, there are two ways, and that is by boat or by air.
Air Tahiti flies from Papeete to 42 airstrips in French Polynesia.
There are a number of inter island boats which run regularly between the main island groups, and this is an incredible way of getting around this part of the South Pacific. There are huge catamarans that run between Tahiti and Moorea, but of course with the pressures of modern life and the probability that your vacation will be two weeks only, then flying is the most likely option for most people.
On the other hand French Polynesia is probably a once in a lifetime vacation, and you will have been flying for around 24 hours if you have come from Europe, so at least a month would still not be long enough to see...