I'm getting my wife two lighted shower heads (~ 1# each) to replace the two in our existing shower. The shower has a standard "L", a splitter, a shower head w/ pause on one leg, and a jointed 2" long extension arm w/ another shower head w/ pause. There is also a "Shower Cleaner" thingy hanging from the arm. See photo. The shower itself is only 2.5 / 3" wide.

I've been concerned about the extra weight I've already had, and with the extra 2#, especially the one on the far end of the extension arm, I'm REALLY concerned about ripping the shower head plumbing out of the wall! It already has a fair bit of play in it.

Questions:
1) Should I be concerned, or is another 2# nothing to worry about. Actually, it will likely be 2.5#, in that I will need to put shower pause buttons inline with each of the new heads as well.
2) Is there a standard shower arm extension bar available for just such concerns (I haven't found it, but perhaps I don't have the correct term?)
3) Which wall should I attach it to? To equally distribute the weight, physics says the far (left) wall, away from the shower "L". But, if I want to reduce the load on the shower arm as much as possible, then I should mount the support FIRMLY to the stud directly above the shower L. Which is the preferred? Note that the shower is so small that mounting it from either wall is about the same distance.

Thanks in advance for any answers.

If your shower arm was installed correctly you will not have a problem. The shower arm is screwed into a dog ear elbow which is normally securely screwed to a stud. The cleaner and the extra arm are not applying identical forces so not a big concern. The cleaned appies shear straight downword and the arm would applyan arcing or swinging pressure. You could attach the cleaner to the shower wall with double faces adhesive made for this application or by drilling a screw hole but I would not bother unless you see movement or wiggle