Because different geometry create different ride characteristics, and depending to the type of riding people want to do the want a bike that fits their use. A slacker head tube angle makes for a more relaxed steering respons. Good for cruisers, Dh bikes and touring bikes, not so nice for a road race bike.
two wheels attached to a frame
All the net has to say about Gramaglia bicycles is that it is/was a small italian bike builder/frame maker who did road and/or track bikes.
Yes it can, many people have made bicycles with wooden frames.Wood is light and strong especially laminated wood. If you search on google images you can see some wooden frame bicycles
yes they did use bicycles but different ones
Not really, they're one out of several good bike build techniques.
Bicycles rarely become valuable collectibles, so probably no.
4
The frame number can usually be found on the underside of the bottom bracket. With that you might be able to track down the year-if you find someone who can tell you how to decode the frame number.
Cadel Evans will have a herd of bicycles to choose from, and they may have different materials in order to make them better suited for a certain type of riding. But the probable answer these days is Carbon Fiber.
I do, I've built a couple. Usually starting from a naked frame, although I've built frames too.
I think they looked a bit like todays only a single bar frame and no pedals
4.