ok after days of reading I think I'm starting to understand the basics of how everything works. Correct me if I go wrong please. There is a kernel on the phone (like a BIOS for a PC) and then we apply a ROM over the top (like an OS). The kernel is locked but we can change versions of the kernel just not to a previous version number (without difficulty). The kernel can be applied by either an full flash (SBF via RSDlite) or applying a kernal (.zip file via bootloader). The ROM can be applied via the bootloader. I understand how to root the phone and apply 2ndinit so I won't go into that.
So where am I at now. Before I fully understood all of the above and having had experience with a HTC desire I plunged in and rooted my phone, applied 2ndinit and then soft bricked my phone when trying to apply WhiteRabbit V1.3. I figured out how to fix that by applying a SBF (DEFYPLUS_U3_4.5.1-134_DFP-1321_CN_SIGN_SIGNED_UCADEFYEMARAB1B50AA009.0R_PDS0 3C_USAJRDNGIBRIRD15_P014_A026_HWp3_Service1FF.sbf) and repeated the process.
I've tried to update to V1.4 but it errors during the install with "tweaks.prop". I tried following the instructions in the whiterabbit installion video www_youtube_com/watch?v=B_tRpwurJdM including the CM9 kernel that listed but after applying the kernal I got a bootloader error so I started from scratch, applied the SBF above, rooted etc and then reverted to my full backup.
Now I have the following:
Kernel 18.104.22.168-gbdd614etvwm73@zch45Inxdriod54 #1
Rom WhiteRabbit V1.3
What I don't understand is why the WhiteRabbit V1.4 does not work? I suspect it's because I am using the wrong kernel but I don't understand how to select the correct kernel and I want to avoid just blindly applying kernels without understanding why and ensuring that I don't end up with a kernel that I can downgrade from.