altremote_update - application image mode

1) Param 4 is the boot address (cannot find reference to addr/4 in AN521, see table 4).

2) The image will be bootable if moved from 0x0000 to your new boot address. Unless you have a Nios processor with software for the image. In that case you would have to modify the nios bootloader. (Its just changing an address)

3) You may read the altremote_update registers or perhaps use signaltap?

Note that reading the registers of altremote_update for Cyclone III and IV is a bit confusing. The parameters are available at different read_source settings. See table 4 of AN521.