feature image confusion

i’ve read a few other threads about this confusion but i wasn’t able to follow the explanations…
I’m having difficulty getting an image in a post to show up on my home page next to the post, on the actual post page, and on the category page.

If i choose the image as a featured image and don’t insert it into the actual post, it appears correctly on the home page and the category page, but if i click on the actual post there is no image on the post page.

If i choose the image as a featured image AND insert it into the actual post, I end up with duplicate images on my home and category pages, (which makes sense to me) but a correct display on the post page with just one image (i’m assuming the image that i inserted into the actual post)

If i ONLY insert it into the actual post and don’t choose an image as a featured image, for some reason the SECOND image in my post gets automatically displayed at the top of my post above the image i inserted into the post. does that make sense? it’s almost seeming as if another image is being automatically generated as the featured image if i don’t select one myself. :-/

i deactivated my simple auto featured image plugin, thinking perhaps that could be the problem but it didn’t fix the issue.

the only workaround i’ve been able to find (and this is how i’m leaving my page for the moment) is inserting my image into the post, not selecting a featured image, and then going to Genesis-Theme Settings-Content Archives and unchecking the “include featured image” box. For some reason this causes everything to work perfectly on my home page, category page, and post page, but obviously now my archive page shows no images at all next to my excerpts. Which isn’t the end of the world, but not ideal.

I’m a newbie and have learned everything as i go along, so am i missing something really basic here? Please help!
my site is: http://www.littlegreenorchids.com

Thanks so much…