Here's what you need to do...
For bitmaps, tiffs, jpegs, etc...
Setup your new template this way:
Go to edit sheet format before the
INSERT>OBJECT>CREATE FROM FILE>(browse to location) command.
But when trying this, I agree with your statement that .dxf's do not import correctly into a blank template. But I found this work around for you:
1)Import your dxf normally into a blank drawing.
2)Highlight the dxf on the drawing and use the CUT icon on the toolbar.
3)Right click in the background and choose "Edit sheet format".
4)Use the PASTE icon now.
5)rememder to go back to "Edit Sheet" before saving as your new template.
Make all your changes while working under the "edit sheet format" command. Go back to edit sheet (border will turn grey), and save as template.
Any changes done under "edit sheet format" should never scale when you scale the properties of the sheet. If it this does, follow Scott's suggestion of reinstalling SolidWorks.
Good Luck....
Remember...
"If you don't use your head, your going to have to use your feet."