One of the reasons I didn't create a PDF of the scale issues and how to import is because I don't want to spend all this time on it if they are going to release the Segment Editor.
I may just create a click by click tutorial for people until they release the editor.
The other problem with scale is that there are SO many different modelers out there that it would be very hard to give a scale for each modeler. I only use Max so that is all I can give it to you.
Yes, the "images" that you see on the Entity and Segment tabs are basically 64 x 64 BMP's. Really easy to make a screen shot (which is what they do). I personally don't spend the time making them, I just have lots of "brain in a jar" icons, which is the default.
I have written/working on 2 additional packs for FPSCreator (Dark Age Fantasy and Additional Sci-Fi) that I may release later, so I have been all over creating entities and segments so let me know if you need any help understanding them and I will see what I can do.
The other suggestion I have is load up a segment or a character into your modeler and use your ruler tool to get the size.
As for the "Search" feature, I hate it too, BUT I did a search for "Import" and it came back with 7 results. Maybe the search wasn't working correctly when you tried.
Hope this helps some.
-This...is my boomstick!