Hi Yoong,
yes correct it would be:
0xE000_0000 - 0xE00F_FFFF CM4 Private Peripheral Bus (PPB)
0xE010_0000 - 0xFFFF_FFFF Reserved
You are right 0x70000 bytes are 458,752 bytes, 458,752 / 1024 is 448kB - this would be correct. 0.xxx MB generally is not correct. If used then 0.4375 is less wrong. Will make note in shared review.
regarding 0x40070000 please look in secure RM.
/Jiri