I bought Poser but have yet to educate myself save the online freebie tutorials.  Before I spend a great deal of time, I wonder if I might ask a noob question. 

My wish is to create short animated films (3-8 minutes).  I can't draw.  I was hoping to buy precomposed figures, props, etc.  Many I see for sale look fine for my needs.  But, quite often I will need to tweak the prop.  Is it possible to edit a bought prop?  For instance, I need a haunted house with working window shutters.  The buildings for sell don't have shutters.  I'm sure I can create a shutter.  I just wonder if it is possible to add these to the bought model?

Thanks in advance.

Short answer - yes.

Long answer: you'd need a modeling tool of some kind, wings3d and blender are free and I think hex might still be free over at daz.  Then you have to learn to use it.  Then you have a few options.

1.  Create a new prop (shutter) and parent it to the original in poser.

2.  If the geometry allows it you can tweak it to be a figure.  Figures can have bendy parts.  This involves using the setup room.

3.  Tweak the obj file (back it up first) in your modeler and then save it with a new name for use as a morph.  Then you have to load the morph into the original prop in poser.

Sometimes - depending on how the model was built and textured - you can also extract part of it in Poser and then tweak that part (rotate like a door or window, move it). In your shutters example - if the shutters are completely modelled and textured, you can extract them, change their rotation or position. Make the original part transparent and you have a working shutter. You can do this in the groupeditor in Poser. Depending on how it is modeled, it can be very good or not so good. If a single plane was used in the model, it won't have any thickness. For that you need to use a modeling tool

Also, it won't hurt to ask the creator.  Many of us are happy to make alternate versions of a prop if it means someone will actually USE it!   Depends on complexity and personality, of course.....

Yes you can - take your example of a haunted house. I have such a model which currently it's a static prop. Load the OBJ into UVMapper, locate the bits that make up the window(s), assign them to new groups. Save the OBJ and create a poser figure with those groups as body parts. A good poser figure tutorial is here.. http://www.cocs.com/poser/makingfigure1.htm For the freebie house, click the banner and select freebies on the site.

I thank all of you for the quick, layman replies.  I also own Maya.  I know it is more powerful, but I also know it has a steep learning curve.  I love the idea of simply asking the creator/seller of the props - didn't consider that.  Again much appreciated.  I be already started my poser with a beginner video sold here.  This looks like it could be fun.