Hi John!
I see that we have to start from the very beginning (don't hate me if I'm wrong -

)
First of all, you have to define site. You are creating entire site not just one page, aren't you? So now we have to define site:
1) Site > Define Sites... > New. Enter all necessary info. Set the path to the folder on your computer where you keep files of your future (or already existing) site. DW will create site cashe for faster access to files and some features.
Now you can build your site, create new and edit old files. One important thing - all files that you use must be within this directory where you keep your site. You must have all you images (logos, flash, etc.) in the site directory. You must be able to browse them in the Site Files window.
When you need to insert some image (or any other object) DW normally inserts it if this image is within your site root (directory). In this case DW makes path to this file relatively to the site root (like "enter.swf"

. If you want to insert file that is out of your site root directory DW asks if you want to save it in the site root, you must save it in the site root directory. Otherwise DW makes path to this file relatively to your computer, like C:\some_folder\some_image.gif
Thus, the rule is to create/define site and keep all files inside the site root.
Now I'll try to answer to your questions.
1) I can't answer to your first question because I don't know where you have files on your computer, the only person who knows is you.
2) I hope that what I wrote above will help you to understand how to name path to your logo. If not - say and I'll try to be clearer. (it must be the same as with "enter.swf", something like "logo.gif"
Good Luck!