You can not create your own project presets in Premiere Elements.
However, as I explain in detail in my books, both 4:3 and 16:9 widescreen standard definition video use exactly the same number of pixels -- 720x480.
In the case of 4:3, the pixels are taller than they are wide; in 16:9 video the pixels are wider than they are tall.
What you need to pay attention to is the type of camcorder your video came from and match your project settings to it.
The video is actually coming from a cable box for the television network where I work, not a video camera. The source channel is an HD channel, which Flash Media Encoder recognizes as a 720x480 input, since its being converted to a signal my PC can understand via RCA composite cables, which don't support true HD. Do you have any experience with non-camera inputs and working with Elements? Is Elements the right software or do I maybe need a more advanced version of Premiere?
I'm not sure what video format you're working with ultimately, nes. So I can't advise.
But, from the sounds of things, Premiere Elements is definitely not the video editing app for you. Sorry.