SH6601AF (U1) is the controller for the spindle motor and voice coil. It probably also controls the switchmode power supplies (+1.2V Vcore and +3.3V Vio).
88i9045-TFJ2 (U5/U3 ?) is the Marvell MCU.
K4H281638O-LCCC and W9464G6JH-5 (U2) are 16MB (8M x 16) and 8MB (1M + 4 BANKS + 16 BITS) DDR SDRAMs, respectively. Therefore they are different, but I don't know what effect this has.
I have uploaded my HDD IC database here:
http://community.wdc.com/t5/Desktop-Portable-Drives/Datasheets-for-HDD-ICs/td-p/523950
ISTM that the MCUs and motor controllers are identical. The other numbers are RoHS materials codes (eg G4), date codes (122, 117, 1120, 119), batch codes, and country of manufacture (CN = China ?). The date codes are expressed in YWW or YYWW (Year / Week) format. For example, "122" denotes week 22 of 2011.
Your resistance measurements would suggest that the preamp does indeed get its supply from the +5V input, in which case it would probably have been destroyed by the overvoltage. Therefore ISTM that your DIY efforts have come to an end. AISI your only option now seems to be professional data recovery. Sorry. :-(
BTW, your resistance measurements in respect of pins 1 and 10 are puzzling. I can't understand what is going on there.