Tahiti is indeed an awesome place.
For hiring gear, there is Mel (www.tematai.com) who's pretty much every day at the main spot in Tahiti, Mahina.
He is also an instructor and can manage a few nice tricks

This is the only spot in Tahiti where one can rent and get some lessons. This spot also called Motu Martin works in E, E/SE or E/NE so pretty much 90% of the time when the trave wind blows.
The other spot near the aiport, Faaa, only works in a Northely, pretty rare over there and launching is not as freindly.
Then all the islands get the trade winds so as long as the lagoon is deep enough there is a possibility of sailing! Bora is indeed a great spot, heaps of kiters in the lagoon.
Iles de la Societe, Raiatea (where the national regatta takes place) Huahine and surely a lot more are paradise!
Shop wise, there is only Alex who sells from his grocery shop

, Nahoata in Arue. Depending on the year he imports whatever he feels like, it's almost different every year.
From May to Septembre, the wind would blow pretty much everyday.
Enjoy
Remi