You can use a Blizzard 4030 @ 50Mhz ...
Yes. The issue is that the 1.4 ROMs are hard-coded to the 030's MMU. 040 and 060 accelerators won't work because their MMUs function differently so that the ROM image can't be softkicked. Any 030 accelerator should work, but I think there are only 2 kinds, the Blizzard being one of them.
and with softroms you are able to use Commodores Unix for the A3000.
Unix doesn't make use of any special 1.4 ROM features as far as I know. Whenever I boot it, I need to kick in 2.04 first and then use the boot menu to boot from the Unix partition.
Also, I always thought ExtractKickstart was for pulling an updated kickstart off of a SuperKickstart disk, not for pulling one from ROM...