1. The Feds require you ti carry your Passport until you have a GC, I seriously doubt the Highway Patrol have any understanding of visas, until you have your GC.
2. The 30 day privilege is interesting to know, pretty sure my State does not do that,
3. They obviously have some leeway of they choose to use it.
4. EAD works in every State as far as I know, some people get GC before EAD bit that is pretty unusual.
Something for Missouri K1's to know, bit it does reinforce what a hassle the K1 can be.