I will reply with what I understand--I am new here and try to help answer the "easy" questions as my payback to the community...
Yes, the RAW photographs are really raw... However, they are ~10 bit (vs the 8 bit JPEG) and so you can pull some additional highlights and low-lights out of the shots (and whatnot). However, because this is a non-Canon supported raw, there is no "as shot" EXIF data with/in the file. So, you either have to live without EXIF data or shoot +JPEG to get the EXIF data (there is one or several DNG converters that can copy the JPEG EXIF to the DNG file--I think).
The 4GB card appears to be a hard limit at this time for "Dry OS" cameras. Canon requires FAT16 to boot (2-4GB maximum addressable range)--and DRY OS only allows CHDK to load using the "bootable card" method.
The other WindRiver type cameras have an alternate load technique that may not require the FAT16 file system (I am not 100% sure--since I have a Dry OS camera--A720IS--as is the A650IS) and you boot via the "FirmwareI Upgrade" method to load CHDK.
If you need >4GB, you might look at the specs. of some of the Non-Dry OS cameras to see if any meet your needs (12 MB might be hard to find):
For Developers - CHDK WikiThe only alternative I can think of for the 4GB+ limit would be to look at something like the Eye-Fi Wireless cards... I don't know anything about them, but perhaps you can set up a corner reflector or use one of those long range WiFi devices to communicate with the Eye-Fi remotely...
Eye-Fi » HomeAt $90-$100 it might be worth a "shot".
Lastly, if you have not found the posts yet, search for Kite Aerial Photography... Pretty much the same things you are asking for and quite a bit of discussion on scripts.
Kite Aerial Photography (KAP) with CHDK Working Example (one such thread)
-Bill
