Using Odin or Mobile Odin works just as good if you download the .tar version. I Mobile Odin for kernel updates and there is no need to wipe cache/dalvik. Just flash and go
Do not use ICS recovery to flash anything rom related. Kernels and modems are just fine to flash from ics recovery.
Can you give me some examples of what not to flash? I'm using the tREC_v0.2.0 recovery which came with Blazer rom. I flashed a mod to remove the "Swipe to Unlock" text from the lockscreen and didn't see a problem.