We would do a backward roll off the panga at Wolf and Darwin, and swim hard to 60-70 ft where out dive guide would station us until a whale shark went by, then we would swim like crazy to try to get along side. By then we would be low on air and have to swim into the blue and surface. If you surface near shore you run the risk of being pushed into the rocks and the panga can not pick you up. A reef hook is ok in the current, but not so good in the surge. It is better to just hang on the rocks with your hands and enjoy the spectacular show in front of you.
I used a 7 mm wetsuit on my trip to the Galapagos, but in retrospect a 5 mm would have worked. Wolf and Darwin the water was 78 degrees and the southern sites were 73-74 in late July. I would suggest kevlar gloves since you are holding on to boulders covered with barnacles for your dear life so you are not swept into the blue with the currents and surge. You will tear though regular gloves quickly. You will experience what it is like to be in a washing machine, but the trip is well worth it. The fish life is wonderful, schools of sharks, rays and whale sharks as big as school buses.
The problem with the different "Gucci" (colored) o-rings is that if you do not use their proprietary lubricant the o-rings can swell.
There are two ways to get around this, one exchange all your o-rings for black buna o-rings or two use a lubricant that is compatible with the different o-ring materials. I have gone the second route. I use Tribolube 71, but Cristolube 111 also works. I have used this lubricant going on five years with my black, blue, yellow and red o-rings and have found it works well. Please note that only a light coating of lube is all you need so your o-ring seats properly. Also, these lubes are used to rebuild your regs.