I'm not sure I understood your question well, but I hope this applies and helps....
Due to LR not working with a browser, it acts as a Import Export tool with Browser and only when doing this action visible. OTHERWISE you are looking at a file structure that is ONLY created specific to the catalog created.
Having many frustrations in the beginning, I went back and took it step by step as how LR works. It is only a module and can only see image files of TIF,RAW, JPEG, older PSD files. Further You cannot browse a folder on you system and move it to a catalog that isn't open.
If you use ACDSee, this does have a database in the background and you can use it simply as a Browser/Explorer, yet have the speed and flexibility of a catalog with abilities of a DAM.
I was hoping I could use LR as a DAM, but with the limit in formats and the lack of ability to see anything other in the folders it creates, I have to resort to LR as a RAW Processor of some files, C1 to develop other raw files, ACDSeePro5 to manage files, and PhotoShop to make edits.
I have tried MediaPro, and as of 1.3 which I am trying out now, has issues with thumbnails. Bridge is horrible with network drives, and since ignored it and removed all the 2 file cache files it creates in every folder. IDIMager is OK, yet a bit frustrating on the way it makes export files other complicated things that should be simple.... and sometimes thumbs are not working right.
*So for your specific needs....I would suggest to manage your files using a Folder structure you make in Windows Explorer and then simply allow LR to make a catalog over the structure to work with them (letting LR make its own separate structure, like using dates).
Use LR to get the images off a card and onto you main image folders and allowing that to be added to your specific catalog. Use Explorer to move images around and have LR Sync/update the content. This is how I work around LR's handicap.