I'm glad you like, we aim to please :D
CharPad supports around 500,000 character images for the image import if I recall correctly.
Only 256 are allowed in a single char set on the C64 of course.
CharPad already supports export in formats greater than 8-bit but these exports are currently only available as text/asm exports as I recall so take a look at that part of the Import/Export menu.
8-bit, 12-bit, 16-bit are fully supported.
Formats larger than 8-bit can be useful for tile-maps where > 256 tiles may be used or for the bitmap modes where 1000 character images are effectively made available/viewable on the C64.