The skin needs a few modifications if you do not compile it with the addon code. now that you have the skin running open up your skin folder and open the apps.xml file. in there look for the item with the name 'media_list_box' and change it to 'apps_list_box'. if you look at the 2 items above that one has a name of 'page_up' and 'page_down'. the action has 'apps_list_box' in it so this is the list box it is looking for, the skin has an error and for some reason has the name 'media_list_box' instead of 'apps_list_box'. also in the page up and page down items, after 'scrollUp' and 'scrollDown' change the 9 to an 8 because there are only 8 items in the listbox-another error. anywhere in the skin where there is a page up and page down you need to change the 9 to an 8 like in the music library and video library. if there are no apps in there run 'nscan' in the terminal to be sure it builds the database file. the file is located in your user folder under .nghost. look and see if the file is in there. if you remove the top panel you need to install something like wifi radar if you want to connect to wireless devices. without the panel the nm-applet is not really useable.
the top bar is a matchbox panel. open up your /etc/matchbox/session file and in there you need to comment out a line, i cant remember which one it is but is says something like matchbox-panel or something, i think its right after the nm-applet line.
obd2 have no idea, don't use, tripzero could probably point you in the right direction, or search the forum!
gps was simple for me, i plugged my receiver in and that was it. open navit with you receiver plugged in and see if you have green or yellow bars at the top of the screen-this means you are getting signal and everything works. but remember you have to have a map file for it to display everything. download the planet file if you want link or go to the openstreets map website and download the portion of the planet you want. the .bin file needs to go in to the /usr/share/navit/maps/ folder (the folder should already be there).