I cannot answer the first 2 questions as ive palyed 2 games of STW WE but the 3rd i might be able to help you with.

On my first game (shimazu 1530) i realized the same thing. My solution was to allocate certain areas to the production of units. You may not get as much units per turn, but all the units are easier to find and you can always allocate more areas to the production of units as needed. As your empire grows your 'unit camps' can continue to change.

This way your troops are quickly at the front line, easy to find and if a certain province is good at building a certain type of unit the you could just constantly churn out that specific unit(s).

hope it helps

Makedi