Mapswitcher - What does this do?
What is the different between NT (navteq) and TA (TeleAtlas) maps?
How can I run Garmin maps?
What is AutoKarta?
What are some of the external programs you can run?
Are there better voices then just the default female voice?
What other non-navigation related things are people doing with this?
How the heck does this new russian mod work, it seems to do things that weren't supposed to be possible?
Well, I can try to help you out on some topics
1-Mapswitcher - All navigation systems come with either Navteq maps or Teleatlas maps. Garmin relies on 'Navteq' whereas 'tomtom' maps are based on 'Teleatlas'. They both have their advantages and disadvantages. Here in Canada, the Navteq maps were always better because Teleatlas always had missing streets, etc.. That however, has changed considerably with the latest updates as they are now pretty good. The mapswitcher function allows you to switch between these two mapping systems on the fly. The only disadvantage to doing this is, is that there is not enough room in the Avic to place Navteq maps, so in order to install these, you have to delete Teleatlas maps that you do not use (such as Hawai, Alaska, Mexico, etc. as I live in Canada) and only install those Navteq maps that I directly use.
2-What is the different between NT (navteq) and TA (TeleAtlas) maps? - As it was explained above, they are just different mapping companies. In the US, TeleAtlas has always been great, but here in Canada, it has always been Navteq. Eg. My hotel room that I stay at on business is located on HWY2, which is a major highway. This is not even listed in even the newer Telesatlas maps when searching for it. However, using the Navteq maps, it is right there 
3-How can I run Garmin maps?- Why would you want to? The layout and maps are so primitive to the layout of the Avic. I tried to install the Garmin system in my V3.0 mod earlier, and it looked like crap next to my schemes in the Avic, so instead of going backwards in visual functionality, I decided to scrap it.
4-What is AutoKarta?- I am not really sure what the purpose of Autocarta is. It is a function that is mostly used in Russian GPS systems and never has adapted over this way. When trying to do a search as to what its purpose is, there was never an answer.
5-What are some of the external programs you can run?- Every mod is different, in mine, you can run a backup program, you can run 'resinfo' which tells you the memory information that is being consumed as you are using the Avic, you can also run 'Total Commander' which shows you the file structure and allows you to work in it while having the navigation open. You just cant change any program that is being used.
6-Are there better voices then just the default female voice? - YES, this has been covered countless times in the 'HACKS/MODS' section. Do a search and you will find the answer. I dont use any voice as I always mute it.
7-How the heck does this new russian mod work, it seems to do things that weren't supposed to be possible? - This is a windows system, meaning that any program can run on it providing that it is written for WinCE.