1. Which do you like better, the columns separated into 3 or put together?
Slight preference for together, but they'd both look nice.
2. Does it need a border of white or a color?
It would look nice either way. White would be a stop border, so you'd want to keep that small & probably add a 2nd border after it. I agree with those who've recommended some kind of pieced border.
3. would you move any of the blocks or change something?
I might swap the block in the 2nd row far right with the one in the bottom center just to spread out the yellow a bit.
4. What would you do for binding?
It depends what you do for your border. Playing off the helix pattern, I think a narrow stripe cut on the bias would look really nice for this quilt. Sometimes a gingham creates the same effect so your blue & navy gingham might work.