Comment 6 for bug 1452202

Looks to me like you're "just" missing adding 'priority=critical' on the command-line to avoid being asked for the hostname. This happens before while the hostname is preseeded, the network needs to be brought up before it can be read, and netcfg does both bringing up the network and setting the hostname. Setting the debconf priority to 'critical' avoids the initial questions about the keymap and hostname/network settings. In other words, this means for a fully-automated, unattended preseeded install, you wouldn't need to specify hostname or keymap/locale, as SANDHYA VENUGOPALA suggested.

There still appears to be a bug though, in the way that netcfg doesn't honor the preseeded settings and set the hostname in /target (or in the installer environment, for that matter).

I will leave to your choice whether you want to close this bug report now, or keep it open for the netcfg bug I described, which still matches the title and description.