Hello Bobbi, the first thing that I would suggest that you do is join the AOLP (Association of Outdoor Lighting Professionals). This way you could discuss, in depth all of the items that you bring up in greater detail on the private AOLP forum.
As for software, there is none as of yet for landscape lighting but you could look to Landscape Pro to show a full landscape and you can use the lighting feature in that program but I think it's pretty much a waste of money since the lighting looks pretty bad in those programs.
All designers work differently when it comes to putting together designs and proposals so once again I would look to the members of the AOLP to help you out there. Visit
www.aolponline.org for information.
Good luck,