Fuji 4x5 instant pack film is readily available in the US. While the choice is indeed limited it is good film and fun to work with. There is ISO 100 in color and black and white, and a really nicely-toned ISO 3000 in black and white that I love to work with.
I don't shoot 4x5 myself, so I don't know what pack film holder will work with your camera, but here is one on Freestyle:
http://www.freestylephoto.biz/02405056-Fujifilm-Instant-Film-4x5-Pack-Film-Holder?sc=24100
They might be able to answer your questions about what fits what.
Regarding using the images, you have a few choices. One is image transfer. Here a site with technique:
http://www.daylab.com/Fuji_Instructions/fuji_instructions.html
Scanning the negative of the 3000b gives a faux wet-plate look:
But lately I've come to appreciate the unique aspect of the instant image. Now I think of each one as a unique work of art. If I get one I like, I mount it in a frame, sign it and give it to someone. I've had two framed instant photos accepted into juried shows this year.