Hi Mkn, welcome to the forum !
Firstly (but you might already have read this) here's the supported camera list:
http://chdk.wikia.com/wiki/FAQ#Q._What_camera_models_are_supported_by_the_CHDK_program.3Fyour points:
ad 1: Autoboot works on all supported cams - there could be complications, but only if you need to use a card > 4 Gb :
CHDK can only autoboot from a FAT16 file system, so these cards will need to be partitioned in that case.
ad 2: Most supported cams will do this out-of-the-box when booted in Record/Shooting mode; note that some cams (mostly
models without a physical switch for changing Record <-> Review mode) can not do this
ad 3: Should not make much difference.
ad 3bis: No , you can only change the real firmware (CHDK is software, not firmware) with official Canon updates
ad 4: AFAIK the cheapest supported cam that's still available in Europe is the A590 (i paid ~105 Euro in the Netherlands);
IXUS 80 IS (~ 140 Euro) is also supported. Older cams are almost always supported and might be available cheaply
second hand.
Depending on intended use, there could be other things to consider: IXUS cams, for example, generally do not have an
iris diaphragm, but a neutral density filter instead; AFAIK they don't have a DC-in either.
HTH,
wim
