Good list of needs, but have you set a budget?

Folders usually range from $200-$3000.
Most use standard diameter handlebars but switching to drop bars will obviously change the geometry.
Xootr Swift, Downtube, Tern Verge, Dahon Vector/Dash, Airnimal, and Birdy are just some other bikes that come to mind.
You might consider a separable Moulton also.