A NUDURA ICF wall is effectively a shutter with a solid concrete masonry wall inside. When treated as such with at least C25 concrete the strength becomes clear. It is easy to over specify but when you compare a 25N solid concrete wall to a 7N concrete block wall and the specification that would have it gives some perspective.
A typical specification would be a ring beam at the top of each lift to create the lintels for the openings. If this can be a single reinforcing bar as opposed to a double, even if it is a larger diameter, the placement of the concrete is far easier.
Starter bars are usually only necessary when a wall is retaining and wouldn't be used as standard.