So when I edit audio in the timeline, I use shift + D to split the layer and get rid of the portion of audio I wont be using. However, the full length of the audio clip remains in the timeline
you shouldn't really edit audio in After Effects. it's harder to edit and playing back than premiere (or audition) and it really does not offer much audio tools to deal with mixing. but if you do, this is how it works (for any layer that has a duration source: audio, video, pre-comps) - you see handles for the remaining length of your layer. this should not bother you. it does not render and is only there for a showing you that you actually do have more of this layer source.
making my final video rendition way longer after the last audible sound has stopped.
this is not because of the audio layers but because of your work area. just set it up according to what you want to render by dragging the handles
or using the N short cut for the eNd for your workarea at the current time indicators position.
it seems you are new to this. you should probably read this:
and do a few of those: After Effects tutorials
thank you so much!!!!!!
you're welcome Buddy have fun.