[Samsung Epic 4G Touch] sfhub:
I am reading from mobile so only skimmed through this. Some questions are probably already answered. Excuse the typos, it is a pain to type long replies on mobile.

The 7zip thing is probably because i package everything as 7zip self-extractors, which on windows means you just double-click on the *-sfx.exe and choose the directory to unpack to. The roms are relatively large so compressing them makes sense and 7zip does a better job compressing and is cross platform. Anyway on platforms other than windows you just treat the -sfx.exe file like a regular 7zip archive and use 7zip or other archive tool to unpack, similar to if zip or rar was used to compress.

Regarding why there are bricks, there are two more prevalent ways of bricking this phone.

1) flashing an intl gs2 factory or leaked rom that includes the intl bootloader. On our phone, the intl bootloader disables the usb port so you can no longer recover using any tool that uses the usb port. If you happen to have custom recovery still on the phone, you can use an update.zip to update your rom, kernel, and modem, but your usb port is still useless.

2) using an ics kernel combined with a custom recovery to wipe, restore, or otherwise do partition operations that affect /data. This is not a deterministic brick in that you can have the same operation work fine many times, but then suddenly have it fail. There were some more deterministic variations of this type of brick involving a temp flashed cwm touch, where wiping/factory reset would very frequently cause the /data brick.

So what is the /data brick? Apparently a change in the ics kernel combined with certain custom recovery operations can cause a hardware failure in the emmc memory for the data partition section. This will cause all future attempts to format, overwrite, restore, the data partition to hang or fail. We know it is a hardware failure because even using jtag to bit blast the proper software fails. Often people don't realize their data partition has bricked right away because they are in the midst of wiping/factory reset or restoring a backup. Then something isn't working right so they go and use odin to get back into a known state, but find odin hangs on the data partition. This may lead them to think odin is not working right or even that odin caused the problem, but in reality, odin is just the messenger that your emmc is screwed. The damage was done earlier. We know that to be the case, because

1) in all instances it was traced back to on operation with an ics kernel and custom recovery

2) this type of brick never existed before the ics kernels (linux 3.0 kernels came out)

3) galaxy note on ics has the same type of emmc brick

4) we know there were changes to the emmc code because different areas of emm are exposed in ics kernels which were not exposed in gb kernels

Your only recourse for this type of brick is to return for replacement, as even jtag fails.

Regarding odin, if you are coming from another platform, it is basically like fastboot in that it is a failsafe type flash using low-level bootloader routines which do not depend on working kernel or rom. Most types of soft brick can be easily addressed by odin. As to why it is safer, it is using low-level bootloader routines so doesn't depend on the ics kernel which we have found to be problematic in certain situations listed above.

Regarding recovery, I also came from a platform where recovery was a separate partition. This made sense to me. Alas, this phone does not use a separate partition for recovery. Instead reckvery is packed into the initramfs of the normal android kernel. if you flash a new kernel, that comes with a new initramfs, and you will get whichever recovery was packed into its initramfs, whether that be stock or custom recovery.

Ironically, there is a separate partition labelled recovery.bin that for some reason is not used. The contents are exactly the same as the kernel, so in the current state it just serves as a backup of the active kernel.

In closing, I would suggest treating this phone as a new platform and don't make assumptions based in past experience. Being android, there are similarities, but there are also important differences/quirks to be aware of which are easily missed if assumptions are made.