We did take the A1 from nongh tranh to hoi an because there is so much to see that we decided to fast forward that part in order to see more of other stuff. Next we ride to hue and then the hai van pass as you mentioned! I'm so psyched!
I know it's not without its risks, definitely didn't expect cows to appear a couple times. We're being as careful as possible, I hope it all goes well :) I swear the road from da lat was the most beautiful mountains I've seen in my life!