Hi Lloyd,
I have never been to the Galapagos, but I've done a lot of research on it as we are planning on spending our honeymoon there next year! So....here's my 2 cents from my research...
The research station is in Puerto Ayora (the biggest town), on the Island of Santa Cruz. The main airport is on the smaller island of Baltra, with many shuttles to/from Puerto Ayora. You fly there from either Quito, or Guayaquil on Aerogal (
www.aerogal.com.ec) or TAME (
www.tame.com.ec).
In all likelihood, you'll have to overnight in Quito or Guayaquil on your way in, and probably on your way out as well. Quito is probably more scenic than Guayaquil, but the latter is more lively. In Quito, check out Cafe Cultura for very special accommodations (with a luggage storage service should you decide to overnight with them on your way out):
www.cafecultura.com
Accommodations in Puerto Ayora: take a look at Red Mangrove Inn (Cafe Cultura's sister hotel):
www.redmangrove.com
Diving: it's advanced diving with strong currents & surge. You have 2 options, day trips from Puerto Ayora, or live-aboard for 4-7 days. If you want to dive at Wolf & Darwin (tons of Hammerheads, maybe whalesharks at that time of year), you need to do a liveaboard upthere (it takes about 1 day to get there!).
For land-based day trips from Puerto Ayora, check out Scuba Iguana:
www.scubaiguana.com
For liveaboards, you can check out the Aggressor:
www.galapagos-aggressor.com
or the many other liveaboards:
www.galapagosislands.com
As far as I know, the dive sites are comparable around the main islands (Santa Cruz, Santa Fe, etc.), but Darwin & Wolf stand out (people call these one of the best places to dive in the world).
The water tends to be colder in the Southern islands (low-mid 70s), as opposed to the Northern Islands / Wolf & Darwin (mid-high 70s). They recommend to take full 5mms wetsuits with hoods, gloves & booties.
In all, Ecuador is a really special (and currently politically turbulent) country, and the Galapagos are one of the most unique places on earth.....
Hope this helps!
J.