Ok there has been quite a few CFW'S released for 3.55 so this post will explain each one and the differences.
There is 4 CFW'S I am going to explain : Kmeaws, Wutangrzas, Waninokos, Geohots.
Kmeaws CFW has peek/poke enabled and allows you to bypass PKG checks, so you can install pkgs. PKG's for 3.41 may work otherwise 3.55 PKG's made with geohots tools will work. Also this has app_home .
DOWNLOAD - http://www.multiupload.com/AXPNFMOCMP . You have to create the firmware using an official 3.55 and the patch inside the rar. You need bspatch then type from cmd - "bspatch PS3UPDAT.PUP PS3CFW.PUP patchfile" MD5 is - 2be5e87a22bf1e7f48e98fcabd38977b
Wutangrza's CFW is basically what flukes1 released with his tools. It just has peek/poke enabled after you run lv1dumper but you can't install PKG's.
Geohot's CFW allows you to install special signed PKG's that have been created with Geohots tools. Can be installed over the top of most CFW's if needed. This does NOT have app_home
Waninkoko's CFW basically modifys LV2 KERNEL inside the Firmware. So when you flash the firmware you a flashing some files that have had lots of user changes in it. It has all the syscalls in it etc and can install PKG's. Basically it is like what 3.41 was when jailbreaked. BUT this FW is risky and has caused bricks and shouldn't be used. You can get all these features by using the add on patch below.
This FW can cause BRICKS.
Kmeaws also created a LV2.pkg patch that can be loaded from any CFW that has peek/poke. This patch adds syscalls and the patches PL3 payload did into your LV2 memory without risking any bricks. It allows Backup managers to work. When you restart you PS3 it is back to standard. You have to run the pkg to patch the firmware to use after each restart.
On Wutangrza's/Geohot Firmware you have to use pkg's signed with geohots tools.
On Kmeaw's Firmware you can install any pkg. Like the ones from 3.41 and ones signed with geohot tools.
LV2.pkg is a program that is run from the XMB and patches the memory to add syscalls to allow bm's to work and other things that PL3 did. There is no risk of bricks using it.
All Firmware above is safe to install from XMB Except Waninkoko's! (Which you could get a brick)