HI
Used to work in Rangiroa as did Mike Veitch, we both used long free diving fins and found these to be an excellent choice. Grab yourself a reef hook as well so you can hang into dead coral and rock with out damaging other stuff.
Avatura pass used to do the Silvertips dive, which also had the school of Trevally on it, that was a good option to do.
The outer reef of Tiputa pass has great turtles on it, as well as mantas.
The passes can be fast which is where a reef hook comes in handy, the Hammerheads were more towards February if I remember but you never know.
Lens wise, 16-35 would be a good choice, when we were there it was Nikons V 15mm lens mostly, or I used to shoot my 20mm with an N90 (Nikon).
Its a fun place, the currents bustle you through the pass on incoming tide, outgoing the water becomes very green and not the best time to do the passes.
At the end of Tiputa pass is the Aquarium dive site which has a small motu (island), if the current is screaming watch you dont end up on the motu. If the currents are not working (sometimes weather can shorten incoming tide times), then there are the corners and reefs outside, which have the turtles, mantas, eagle rays etc. There is some macro around it just depends on whether you can stop to take a photo of it.
Plus the bottlenose dolphins will hopefully show up, truly amazing in the mouth of the channel. Keep your eye out at sunset we saw some amazing bait balls with birds feeding which made for some cool land shots.
Hope this helps in some ways, Mike may chip in if he is on line.......
Have a fun time, and also enjoy the french cheese and bread!
Karen