I just went through the training a few weeks ago and the nurse recommended giving the shots in the stomach. It was no big deal (a lot of padding there, in my case

). I do not have the pen, but the people in my class with the pen still got the instructions to do it in the stomach.
The trigger shot just depends. Is it a SubQ (just below the skin) shot or an IM (inter-muscular)? For me, the trigger shots are IM and with a 1.5" needle (compared to a 1/2 inch to a 5/8 inch for the SubQ shots). If I were to give them to myself, it would have to be the thigh as that is the only muscle I can get to. However, my nurses recommend having DH go to training with me and have him administer the shot in my butt.
My neighbor is a nurse and she gave me my trigger shot in the thigh last week. I do not think I can do that, so DH is going to training tomorrow to give me my booster shot on Thurs.
Good luck with the injectibles. Those pens looks nice!! I don't think you'll have a problem at all. I found mine surprisingly easy.