Lightroom question -lost photos

Can someone explain how to import, and then after editing how to get the photos back to where i want them?  Sorry if its basic but for some reason after editing my photos in lightroom when i export them, all of the photos dont get exported???  i dont know why.

I usually use capture NX but am looking for the easiest and FASTEST way to edit photos.

With lightroom i like how easy and fast it is - but why cant i just edit photos in an existing folder?

Any help is much appreciated!!!

Basically i just want to quickly go through a folder of images with basic edits mostly to JPG's.  I can do raw in capture NX quickly.  I wish i could edit the photos in their existing folder so they did not move around

Also when editing in lightroom do i need to save each photo or can i just make adjustments and move on to the next and then the next and so on?

thanks all!