Drive partition clarifications and win8.1 rollback to win8

Question

Please forgive me if I have this in the wrong category, and a bit wordy.
Model Dell XPS 18 with i5 and 500gb HDD and 32gb SSD.
The primary drive was repartitioned into a 120gb drive for the OS and a 324gb for files. 
Under disk management there are shown 8 partitions:  500mb EFI system, 40mb OEM, 490mb OEM, 120gb Primary with boot page and crash dump, 350mb recovery, 324gb primary for files, 10.42gb recovery, 8.97gb OEM. 
The 32gb SSD drive only displays an 8gb hibernation partition. 
Within the Intel Rapid Storage program it lists both the 8gb FFS and a 22gb Dev_Cache.
Why are there 2 recovery partitions (350mb and 10.42gb)?
Why are there 3 OEM partitions (40mb, 490mb and 8.97gb)?
I installed the win8.1 update and intend on restoring the machine back to win8 with a Dell OS recovery and Restore USB Key.  My understanding is the Win8.1 update deletes the original Dell win8 recovery image.  If there is no more dell recovery
image available, can the OEM partitions be removed to recover space?  Future file and image backups can be managed via windows.
The XPS 18 machine does not use windows method of hibernation, but uses Intel Rapid Start with the hibernation partition on the SSD. 
Because the hibernation data is on the SSD drive, can the 6.6gb hiberfil.sys file in the root c: be deleted without any performance hit or other issues?

Answer 1

Thanks for your response.  Dell sent a restore flash drive, and yes the MBR of the EFI partition remained as win8.1 after the restore, and yes, all the Dell recovery data is wiped clean with the win8.1 update.  Only after the EFI partition
is deleted, corrupted or reformatted, only then the restore flash drive creates complete new clean partitions on the entire drive, and just 2 of the them: EFI and Primary, all back to win8, shiny and new :-) 
Also, my testing indicates the hiberfil.sys file is not needed with the Intel rapid start partition on the SSD drive, and the pagefile.sys can be set to a very small size when using the Intel rapid storage with the SSD drive.  This saves another 12GB
of HDD!
Here are some comments I want to share with others that will influence your decision to update to 8.1.
Win8.1 is not a simple update, and there is almost no chance of going back without the original restore discs.  Even so, if the restore utility does not see any corruption, it won't restore the MBR.  The result is you might
have a Win8 OS with a Win8.1 MBR.  When you make a recovery flash drive, it even tells you to label it as win8.1.
My main issue with Win8.1 was the lack of system-wide XP style scaling.  With a 1080p monitor, and scale set above the 125% standard, results in MOST programs text looking fuzzy, and MOST windows dialog boxes and windows utilities too.  The
programs can be set to XP scaling individually by changing properties, however the windows dialog boxes and built in programs cannot.  Until this is corrected, no win8.1 for me.  They claim it is due to the up and coming 4k monitors, and if they
let you globally set it to XP scaling, the program text would be too small to read.  Maybe so, but let me make that decision.  Moreover, why do windows own programs and utilities do not scale properly and look fuzzy.  This is a deal breaker. 
The start bar in win8.1 is only a little better, however there are many programs (like classicshell) that correct it to be just like win7 or vista or even XP.  There are programs that let you set the metro background image like 8.1 too.
I wanted to share the results of my experience and research.