First of all, it's hard to brick the tablet completely. I also have had the situation that it hanged at the start screen, but when you just push a paperclip at the reset-hole for half a minute, after that I could always re-flash my tablet again from my PC.
Be aware that there are 2 versions of the tomtec tablet (we call it the 2011 model and 2012 model), so jgelauff made versions for both models. No idea which you should take, but the flashing procedure just takes a moment, so you can just try one out. If you have the wrong one, some things won't work (if I remember correctly the auto rotate function)
I don't use my tablet that much, so don't know all answers out of my head, but just try to help:
1. I think he just forgot to update the topic start, at my tablet it works just fine (also in combination with the clockwork mod). So I don't know any issues.
2. Well, even in dutch I didn't understand what he meant

If I'm correct, there are 3 kinds of memory: space for apps, internal sd-card (/mnt/storage)
and external sd-card (/mnt/storage/sdcard)
In think those 5 versions are something like
- version 1: 2 GB for apps, external sd will be mounted under /mnt/storage
- version 2: 2 GB for apps, external sd will be mounted under /mnt/storage/sdcard
- version 3: 576 MB for apps, external sd will be mounted under /mnt/storage/sdcard
- version 4: 576 MB for apps, other space will be mounted under /mnt/storage
- version 5: 1.6 GB for apps, other space will be mounted under /mnt/storage
I think I use the 1st version from 4.0.3-4 (version with 1GB app space and 1,6 GB internal storage, extra sdcard is external_SD). In most applications it really doesn't matter much how it's mounted, but in some apps I have a hard time getting to to /mnt/storage/sdcard. But in my opinion it doesn't matter much.
3. Yes
4. Yes, at least English. But there are a lot of languages in it, so presumably also Polish
5. No, not installed in one of the roms, but you can install it from that post you were referring to, but it only works on 4.0.3-4 (so don't use ones in the topic start if you want the clockwork mod). I will translate the post for you
clockworkmod with touch menu for the 4.0.3-4 roms
http://dl.dropbox.com/u/77151040/recovupdate.7z
Installation assumes that the right drivers are already installed at your PC.
!!Don't use this at the roms of user redah, because it uses an other parameter file and it will brick your tablet!!
Unzip the .7z-file
start rkandroidtool
turn off tablet (hold down the button, and choose for a complete turn off)
press and hold the esc-button on tablet, while connecting it to the pc with the usb-cable
in rkandroidtool, you should see 'Found RKandroid'
don't change anything, just press run (<-- I think I did a clear first)
if it's ok, it will automatically boot
disconnect usb, and wait till tablet boots
Now go to play store
Install rom manager
Choose flash clockworkmod recovery
confirm phone model kies ultimate10
Choose yes
Choose clockworkmod 3+
5 (for the second time

). No, unfortunately
6. Yes, with adb. It's in the start post, under 'Tutorial voor het Rooten van je Tomtec Ultimate10 Android 4.01 tablet'
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