Well, that's a lot questions.
First of all, download your own photos in a batch is possible, but depend on size of your gallery, it could face a problem. Through web page, you can only download files one by one, or the server has to pack all stuff into a zip file (or RAR, or whatever other compress format). Download one by one is not a choice, compress everything could also be impossible (1000 photos could take as much as 1GB space, and JPG files is not well-compressible). Download all photos by category (folder) might be an acceptable workaround.
As for the catastrophic events, the server which hosts airport-data.com has a RAID 5 configuration, so lose one hard drive will not cause any data lose. I download all photos through internet and burn them into DVDs once in a while, as a backup, but it's behind schedule. Onsite backup has been in my consideration, but with so much data it will take some effect (both mental and financially) to do that.
Feedbacks are welcome, as usual.
Ken