A giant one foot rubberband would work too
I work in a gun store I highly recommend looking into the Ruger SR-9 or the Compact SRC-9. They are great guns that run around 440.00 It has many good safety features cheap to shoot. The 380 ammo is pretty expensive compared to shooting 9mm. I also like the Glock 9mm the Springfield XD but you are looking at around 550 for those. There are many guns to choose from, I recommend you go down to your local gun store feel the guns in your hand. You have to be comfortable holding it. The bigger the gun the less recoil you will feel. I myself carry a Smith Wesson MP45 a Smith Wesson MP 9, I love both of those guns but they are more than you are looking to spend. I also carry a Beretta Nano 9mm for my Concealed carry gun. If you are really looking for something cheap, you might consider the Smith Wesson SD9, they run about $350. Not to bad a gun. Everyone has an opinion but you have to like what you buy.
Any 3/4 fitting will work. Go look in any place that sells PVC pipe and you can find almost any fitting you want. The one you have pictured should sell for about $1 Use schedule 40 This one should be a 3/4 female adapter with feamle threads one one end and will slip and glue on 3/4 pipe
If your daughter has started to curse at you then it usually means that she has little respect for you and she finds you to be a push over and she thinks she has the control. If you let her get away with it then it will only get worse. You have to show her that you have the power, but at the same time try showing her that the two of you could get along and it doesnt always have to be fighting. If going to her fathers house is making it worse, then have a serious talk with the father and get him to set some standards for your daughter, but if he wont do that then you will have to set more standards for you daughter. But you also have to make sure your daughter doesnt take it the wrong way. Some times when parents take to many things away and restrict their children to much, the children rebel even more and do even worse things. good luck and i'm sure it will all work out for you.