Is it possible to make drawings or use symbols like arrows, rectangle or circles and place it in a free track to point out some highlights in the piqture og movie?
You can make any graphic overlay you want in your usual painting/graphics editing program eg 'Paint' that comes with Wndows OS. I use a free photoshop sort of program called Paint.NET.
You've two choices to make the background transparent. If it can be pure black, white, green or blue you apply the appropriate chroma key effect. Of course you can't have any of the chosen color in your symbol as it will be transparent too. Not sure if it's for all versions of MEP, but a file name ending say in "_blue.jpg" will have the blue chroma key effect added automatically.
More versatile though would be to use a .PNG type file which can carry with it a transparency mask.