Programming file format problens in remote system upgrade application?

Hi all,

I'm new in Nios and I'm using remote update controller (cyclone III) on my Cyclone III board with EPCS16 flash. I want store the hardware images(including factory configuration and application configuration) and software images in the EPCS flash and run the nios program in an external SDRAM. But I encountered some problems:

1. What kind of programming image(i.e. the format of programming images, .flash, .ttf, .rbf or any others) should I upload to the target board through UART?

2.How to get these programming files?

3.Should I upload hardware images and software images separately or concatenate them into a single image file?

Any information and suggestions are welcome.

Thanks,

wei