If PSE8 has the ability to use layers and layer masks, it is not all that hard. With your photo opened up in PSE8 duplicate the layer. At this point I always delete the original, just to make sure that I don't trash it somewhere during the editing process. Next add a clipping mask to your "copy" background layer, it should be white. Next step would be to open your new background photo and place it BELOW the background copy layer. (you will not be able to see any of your new background yet.) Next, using a BLACK paintbrush, and with the clipping mask active and selected (you will see a small border around the mask to lety you know it is selected), start painting over the areas that you want the new background to show through. If you make a mistake, switch the color to white and paint back over the mistake. The first few times it will look like c..p but in time you will like how it works. OK, so somebody fill in the blanks of what I missed.

Welcome back to Michigan Canoe50d. Glad to have the prodigal Michigander back :D. Legally there is no problem and, if you're not intrusive, there is no moral obligation either but I like to go up to the house and say "Hi." I find that if I have my camera in hand it's much easier to walk up to their door. If they see you approaching with a camera they'll be puzzled but not likely threatened. Most people are flattered that you find something of theirs photogenic and are all too happy to share their scenery and a story with you. I know what you are talking about when you mention farm scenes, I too am drawn to old silos, stone walls and rusty farm equipment.