Wow, typically - I spent the whole day at a seminary and everyone posts at breakneck speed

Hopefully, I haven't missed anything:
- Purchases:
Ok for everything, but i'm pretty sure the speed loader is for a revolver.
The server costs 300 Nuyen rent
I rule the cost for water, food etc. in your lifestyle are 10% per person of the base cost (since that's the additional cost if you share a lifestyle)
- Underwater magic
The effect is certainly not as strong as pure earth, but it becomes more and more difficult the deeper you go. Especially the high density of biomass will prevent easy astral navigation and only beast and water spirits can manifest without problems. The thick algae carpet on the bases outside alone would prevent any projecting mage from entering. All in all, you'd need serious mojo to find and get near to an underwater base through the astral.
I'd also refer you to p. 157ff in Run&Gun for under water operations and magic. You might find the section on underwater bases especially illuminating.
As far as I can see, bnc's arguments hold water
