First thing, I'm glad that I didn't have to resurrect this thread as it's not even 1 year old. That means that I will hopefully not just make an archive post for myself, but also provide information for others and possibly even get more info from you.
I was also confused while trying to get Porsche Unleashed to run on Windows 10 and also to make it the best version available.
What I quickly figured out by comparing files is that it is best to
install NFS5 Essentials first, then Complete Patch.
NFS5 Essentials doesn't even make the game playable in Win10 as it doesn't have the needed dll's in Drivers folder for use with nGlide. So this fact alone suggests it is better to install it first.
It is most useful for the 40 fixes, most of them are for Evolution mode. I have no idea how necessary they really are, but looking at the list, they mostly corrected historic discrepancies.
As for Enhanced Patch and everything else from iplounge.net Downloads page, I don't think any download is needed if you have the above 2 patches.
I also wanted to know what each file does, so that I could decide which ones to keep.
NFS5 EssentialsFEData\Data\nfs5.car - unlocks all cars, I guess it is not needed for the 40 fixes that are listed in the Game Fixes and Extras.txt
Not needed files:
gimme.dll - size 4.599.863 B, in Complete Patch it is 5.120 B, but I don't know what I can conclude from this, I only know from past that it is a memory manager as it wasn't advisable to delete it in Win XP. And that low size in Complete Patch suggest they removed a lot of things from it, so I'm not completely sure here.
Porsche.exe - only because the file is newer in Complete Patch, 29.12.2015 instead of 11.10.2011, I don't know which is actually better
SaveData\8Player.sav - before you get to the main menu it crashes to desktop, but Googling today I found this is a known issue
Complete PatchPorsche.exe - fixed exe so that you don't get low quality textures, of course V3.5, I haven't compared anything else, let alone in HEX viewer
Drivers\dx7z.dll and voodoo2z.dll - needed for the game to work with nGlide
GameData\CarModel\carcmn.fsh - Chrome Patch, and a very good one, I haven't yet tried all of them from nfscars.net, but it's way better than the 14.2.2004 one, Reflection Mod by SPYRacer
GameData\Simulation\CarData\993coupeS36.sim - I think this file is for "Fixed possible speed boost for the 993 Carrera S" which is listed in readme_mod.txt
It is also a file in which it is easiest to find differences in HEX viewer, as it is only 328 B. Before that, I didn't even knew I also have to watch for file dates, as almost all fixed files in these patches have the same size as original files from 2000.
Not needed files:
FeData\Locale\festrings.loc - the file is original from V3.5 with date 3.4.2000, in NFS5 Essentials it has date 25.3.2015
GameData\DashHud\speedKN.fsh - same one is already in NFS5 Essentials
I don't exactly know what it does, but my first guess would be that it has to do something with a speedometer.
I think this describes it, from NFS5 Essentials readme:
34. Porsche Boxster, 911 (996), GT1 and GT3 now uses the correct HUD KPH speedometer types at night.
From Complete Patch readme:
- Fixed dashboard meters/headlight bug after driving on night tracks.
- Fixed wrong speedometer for some cars when driving on night tracks.
And then I also have a Porsche 928 dilemma.
NFS5 Essentials
928d.fsh and 928l.fsh - date 10.12.2002
From readme:
30. Accessing the showcase of the Porsche 928 GTS no longer crashes the game.
Complete Patch
928.crp, 928.tpg, 928D.fsh and 928L.fsh - date 27.1.2011
No info in readme.
I haven't used these, as I don't know what they do and I haven't found any differences with HEX viewer (I'm not saying there aren't any).
EDIT 2020_07_26 (actually already found it 2018_08_09, just didn't write here):
Here is the answer about these 2011 files, they're already included in addon cars files:
http://www.iplounge.net/ipl2/forum/viewtopic.php?t=2507