1. dark medieval age
hmmm
It souds like a horror but not as something historic accurate.
The roman development in science, tehnology and geography came to a dead end at a certain time not only military but also intelectually. May be the late romans had more luxury as in medieval time but scientific and social development was seriously handicaped by the slavery. Work couldn't be made more efficiently because was done by slaves.
The medieval age faced many challages and during this time the human intellect developed mostly exacly in Europe. (where this dar age existed)
How else after the end of the middle age Europe conquered America, Africa, Asia and Australia with his technologycal superiority ?
2. It is may be as in the MTW1 but in reality crossbow didn't shut so far or even more as bow.
3. Longbow never shut more far than a good reflexbow. Everything else is a legend like the legend of king Arthur.
Bow making never achieved in western Europe the same level as in eastern.
Longbow was made from a single peace of wood, a relative cheap construction.
A good reflexbow was made of wood and many thin layers of horn during 2 years.
Do you think that in eastern where the must archers ever existed they were so stupid to make something so complicated if they could make it better from 1 piece of wood ?
The longbow was only the best bow in western Europe nothing more.