drawings not to scale

What units are you using?
Default units are pixels, that are useful for screen but not for print. When you print using pixels you'll get a default output resolution of 90 dpi.
To change this select a template with real world units or change the default units in the document settings.
Please keep in mind that you need to save, close and re-open the file to get the selected units in every part of the UI.

hth,
Gez.

I made all the settings in mm for several of the drawings using the document properties. Grids and page size. One drawing was set to inch. They were saved and sent out for quote. The quotes came back with wrong dimensions. I then tried printing and discovered the prints were over-sized too!

If I re-open a drawing, the document properties are back to px. So apparently, saving the drawing doesn't save the document properties. Oh, if I select mm, the correct size comes back. So I'm wrong, you're right.

Oh, another discovery...if I print from Inkscape, the drawings are correct size. If I just send the file to the printer from the file manager, the size is quite larger. Would this explain why the quotes came back with wrong sizes? Whoever is doing the quotes has to have Inkscape?

I've had no luck with altering drawings, once I make a mistake it seems I have to start from scratch again.

Mmm. That seems to be a bug. Could you please use the bug tracker and describe your problem? Maybe it's something to be corrected and you're not doing anything wrong.
Please state what version of inkscape are you using, operating system and and what printer is being used.

The about page calls itself 0.46. The OS is Debian Lenny.
When file is re-opened the saved properties come up as px. When mm or inch is selected the correct sizing gets displayed, so the actual real values aren't altered. The printer I'm using is an HP all-in-one office pro L7780. When drawing is selected from file manager and sent to printer the resulting print job is printed larger than it should be (very close to dims. described below). When the file is sent from Inkscape as a print-job the file is printed pretty close to actual size.

When the file is sent to an unknown system probably using adobe photoshop or other commercial application the drawings get interpreted as being larger than actual >>3.456" X 1.0431" for a drawing that should be 70mm X 21mm. This makes it impossible to create a graphical overlay that is going to fit properly onto anything it was drawn for.

Conclusion? Well it looks like printer and the unknown application are doing the same thing. And Inkscape controlling the print job does it right. Culprit has to be with how the file gets saved and re-interpreted. Files seem to grow about 25% in each dimension.

You should try with a development version.
I have .deb files of recent compilations for 32 and 64 bits here: http://www.ohweb.com.ar/screenshots
They were build on Ubuntu 8.04 but I think they should work fine in your system (if not, remove them with synaptic and re-install 0.46 from the repositories).

Check if that fixes your problem