You mean in Blender? To switch from 4 views to one, place the cursor over the viewport and press Cmd+Alt+Q. With the num pad you can switch quickly from different views: 1 - Front 3 - Left 7 - Top 5 - switch from orthographic to perspective Also, in the bottom of each window you have...
Yes, you can import a vector plan and use it as a basis. Well, I use Illustrator to make plans of real builds, no 3D needed to make a guitar, although it would be useful if you're creating some concept, like in the above images.
I use Blender, a free and powerful 3d software. Unfortunately, I can't find any guitar modeling tutorial, but you can start learning modeling from here: blender.org - Tutorials More advanced tutorials: Tutorials | Blender Cookie Blender Guru | Video Categories Archive | Tutorials...
Too late for inlaying, IMHO... I mean, with frets and so on, it would be a living hell... just keep the fretboard clean, it will looks very nice as well.
I think it's easier than sketchsucks, however, guitar modeling requires specific techniques and some advanced skills... Anyway, it depends on the model, so good luck in your travel.
I never use rulers in 3D, but yes, most 3d programs let you work at almost microscopic levels... the faster approach in this case would be importing a 2D drawing in Adobe Illustrator or DWG format and start modeling over the 2D plan, but you also can start drawing in 3D from scratch. I've...