A few quick answers to the questions:
1. Use the "syslog" boot code to create /var/log/messages, same as with Core.
2. Config is slightly different to allow for systemd. Compare the two configs found below, dCore config is the second one, the window shows the only difference. dCore kernels are compiled on the version of initial release of Core that shares the same kernel version. So modules need to be built using that version of Core. The current 4.2.9-tinycore kernel used in dCore was built on Core 7.0.http://tinycorelinux.net/7.x/x86/release/src/kernel/config-4.2.9-tinycorehttp://tinycorelinux.net/dCore/x86/import/src/kernel-4.2.9/config-4.2.9-tinycore-devtmpfs
@@ -1400,7 +1400,7 @@
-# CONFIG_DEVTMPFS is not set
3. Busybox versions are different, but should not be an issue in dCore. Will update one day, but I don't think it is causing an issue now.
4. Udev, except for that found in dCore-wheezy, is part of systemd. I would first try to get this working without delving into that.
5. Firmware loads fine with me, and we have the same file /lib/udev/firmware.sh to allow for /usr/local/lib/firmware as well as /lib/firmware to be used. But if you would, place the firmware in /lib/firmware to see if there is a bug in that script regarding dCore.
Hope this helps.