1) yes
2) see here
3) go to this post, download the attached script version, follow the instructions in the post, run the manager once (ie, up to the empty selection dialog), and post the resulting trace.txt file.

Hopefully my Windows setup might help someone.
Path to the plugin, (original file, no change).
C:\Users\Odin\.gimp-2.8\plug-ins\addonCollectionManager.py

Path to my config file, (from readme, no change).
C:\Users\Odin\.gimp-2.8\plug-ins\addonCollectionManager.ini

Example paths to resources, (sub folders only, no zip files).
C:\Users\Odin\.gimp-2.8\brushes_storage\Splatter Brushes
C:\Users\Odin\.gimp-2.8\fonts_storage\Celtic
C:\Users\Odin\.gimp-2.8\gradients_storage\AG_Gradients
C:\Users\Odin\.gimp-2.8\palettes_storage\COPIA
C:\Users\Odin\.gimp-2.8\patterns_storage\Bling Text
C:\Users\Odin\.gimp-2.8\scripts_storage\saulgoode

My config file.

I'm not sure what your asking, Graechan?
I've stored my brushes, fonts, patterns, etc.,in Gimp user folder.
C:\Users\Odin\.gimp-2.8
The plugin and config files are in user plug-ins folder (un-edited).
C:\Users\Odin\.gimp-2.8\plug-ins
All resources example,
C:\Users\Odin\.gimp-2.8\brushes
and for MrQ,
C:\Users\Odin\.gimp-2.8\brushes_storage

I think it might be easier for you to move and rename the resource folders (brushes_storage) rather than try to rewrite the code. The plugin's a very clever piece of work as is.

Your Gimp set up is strange because it looks for the config file in "C:\gimp_2_8_0-32bits\pref_1\plug-ins\addonCollectionManager.ini" (is this a "portable" version?). But now you know where to put the config file

If you put the config file where the plugin expects it it should work. But it can be shortened to:

since the rest looks identical to the defaults.

User plug-ins folder.
[user]\.gimp-2.8\plug-ins\addonCollectionManager.py
[user]\.gimp-2.8\plug-ins\addonCollectionManager.ini

Graechan, I'd like to hear from you that you are enjoying this enhanced script, so I will try to give you my way:
1 - clear pluginrc (this step is absolutely necessary, if you don't want to simply delete it, just be sure to remove all the lines related to addonCollectionManager
2 - move into [user]\.gimp-2.8\plug-ins my two files, attached here: the plug-in and the .ini
3 - move into [user]\.gimp-2.8 my four *_storage folders, attached here
4 - start gimp and you should see under Help the four managers and clicking on one of those the list of the sub-folder(s) inside the *_storage folder of point 3
If you succeed on setting up my environment, then change whatever you like in the .ini and the referenced *_storage or whatever else folders you prepared, then repeat step 1 (mandatory) and steps 2 and 3 with your files/folders
Hope you will succeed

..follow-on (because only 3 attachments are allowed)...
I hope you hear good news, when you'll wake up tomorrow morning...

Where the trace file tells you:

C:\gimp_2_8_0-32bits\pref_1\plug-ins\addonCollectionManager.ini

Another way to find:
- Start Gimp
- "Filters/python-fu/console"
- Enter "print gimp.directory" (without the quotes)

In your case this should answer "C:\gimp_2_8_0-32bits\pref_1".

This is the directory/folder where by default the add-ons manager will look for everything (active add-ons directories, *_storage directories, and the config file (plug-ins\addonCollectionManager.ini under that directory).

Won't work.... Graechan hasn't got a stantard set up... His Gimp profile isn't at the usual place (I suspect he is using a "portable" version).

Windoze - hohoho - as per Ofnuts I don't know about a portable Gimp
but
A bit of messing around in a Win7 VM & Gimp 2.8.4 with a C:\gurm resources folder.
Looks to me that it will not work unless everything is zipped, either collections, or as we know single files.
The previous ini file I think is correct, for the test I used a cut down one
#
[all]
enable:brushes scripts
addons_active:{GimpUser}\{type}
addons_stored:C:\gurm\{type}
menu_location:{<type>}
menu_entry:{type} sets...
menu_description:Manage {type} sets...
dialog_title:{type} sets manager
#
[brushes]
menu_location:<Image>/Tools/Resource
extensions:.gbr .vbr .gih .abr .GBR .VBR .GIH
#
[scripts]
menu_location:<Image>/Tools/Resource
extensions:.scm .SCM

The only things to note are the backslash for the win paths and forwardslash if you want a bespoke menu location.

It will hang Gimp (at least it does here) if the resources are not zipped.

video of the test http://youtu.be/vu2UPYIogSc 5 mins.

edit:
A couple more things
Make sure the names of the gurm folders reflect the gimp folders
ie. gurm\brushes = .gimp-2.8\brushes
The bespoke menu entry is case sensitive 'Tools' is not the same as 'tools'.

@Ofnuts / @Graechan
I didn't (and don't) know Graechan's environment, I was hoping to help his trials...
It's so nice and clean that plug-in!

@Rich2005
in my environment (Win 7, 32-bits, Gimp 2.8.4 installed, not portable), Ofnuts' script is working nicely with sub-folders under the referenced folder (e.g. ../brushes_storage, has in it the sub-folder Bubbleset), I didn't zip anything (I did zip the files attached here previously only because of gimp-chat rules)

@dinasset
It does here as well, in linux. Same as you I have the resource folders in the ./gimp-2.8 folder structure. Unzipped folders work ok, individual files are zipped. It was a quick test (Spanish grand-prix was on) and looked like there is a problem if using C:\something and unzipped files.

I see.
Happy for Alonso? I am...

Wasn't that last weekend?

*checks*

Ah, on 4 wheels. Eww.