O.K. Now I have all of these on my SD Card (Total commander - in root directory, skin folder in igo/content, containing extension, ui_igo8_da folders) my problem is that the iGO takes most of the files from the flash memory and therefore all the changes I do on SD Card are not relevant!

you did not put the skin right. extention folder has to be in igo root directory. you should not extract the zipped files to ui_igo.... the skin has to be zipped.
To install a skin, just copy the zip file to this folder "iGO8\content\skin"
in gurjon skin you need also to copy "extension" folder to "igo" folder.
to apply skin go to settings>menu>skins and choose the skin.
then you have to make the skin to be able to run total commander - as it written in gurjon instruction that i posted before.
there is no problem at all with igo running from flash. you just did not do it right.

Thank you so much for trying to help me!
The gurion skin works now on my device. In the instruction, you posted before it is written "LAUNCHING EXTERNAL PROGRAMS (Accessible by defining a shortcut in one of the Short Menus)".
What does it mean "Short Menus"?
In what file I need to put program name (e.g. TotalCMD), complete path to the program (e.g. /SD Card/Program Files/Total Commander/cecmd.exe), launch parameters, as needed and the selected method ( exit iGO and launch, or do not exit iGO)? I guess in some .ini file?

I just cann't find the words to thank you, Miomoshe! Recently, after infinty of different operations, searches in the plenty of forums and just before I almost lose my faith in fact I will solve this problem without the Mio service, it is working now! THANK YOU!
And the solution was: after installing the "gurion skin" I ran the "Total Commander". Using the "Total Commander" I found in my Mio flash memory the file, named "USBScreen.exe". Running this file through the "Total Commander" then the Mio is connected to the PC, the computer began to recognize my device. After that I found the mistake that caused the connection problem - it was the wrong path in "Paths.xml" - instead of calling the AppStartupec.exe file it was changed to
iGO8.exe. After changing it back the connection was fixed again! Thank a lot!