The best thing to do is start your course in your home town up to the point prior to the required open ocean dives which you can do in the islands. Most dive operators are also PADI instructors and will be able to complete your certification. You could consider bringing your own diving equipment if you are going to do many dives. However, it is not necessary for a few dives, since most of the diving centers rent excellent equipment or include it in their rates. Scuba tanks are furnished with BC vests and regulator with tank pressure gauge and depth meter.
Rental equipment is subject to periodic checkups and is very reliable.
No, on every dive, you'll be accompanied by an experienced dive guide who is also an instructor. The guide knows the different local conditions and specific dive areas quite well and will greatly contribute to a very safe and enjoyable dive holiday. This service is included at no extra charge. French Polynesia is among the few places in the world where all these fish can still be approached easily. However, contact with certain marine life should be avoided, but this will be covered in pre-dive briefings.