Hi,
Whenever ive made a sting they are usually a 2-4 second long logo transition, they are usually used to get from one bit of VT to another. I usually use bits of my title sequence as the basis for the sting.
Pal standards : I always work in square pixel comps in after effects and then stretch the final output to an 720×576 D1/DV pixel aspect ratio which i then bring into Final Cut or Avid for output to video.
If you are creating a 16:9 format video use 1024×576 square pixel comp in after effects, if your working 4:3 format create a 768×576 square pixel comp.
Hope this helps