WHere Does it freeze? on the GalaxyTab screen or on the Boot Animation Screen?
Have you done Factory Reset Wipe and Cache data wipe? The solution may be as simple as doing it on CWM.
For the File explorer, HumBerOS' ICS also does not have File Explorer. You need to install Root Explorer to access your External SDCard, under emmc,
or under mnt/emmc folder in root. All these are written in each respective threads, if your read carefully you should've found it before you decided to change from AOKP to HumberOS.