I would make reservations to be on the safe side. O'Hana is usually packed & some people opt not to wait & head over to Kona to see if they can get in there instead It's even worse at dinner.
Yes, make ressies. KONA is WONDERFUL for breakfast. If you like sweet, go for the Tonga Toast (enough even to share!). If you are not into sugar overload, the omelettes are delicious too and we usually get some fruit ... to counter-act the sugar and butter ---
We've been to breakfast at Kona many times without ADR's. It depends on the time you go I guess. But we've never been turned away when they were a nearly empty restaraunt.
We have been able to get in with out a reservation, but that was always later in the morning. Everytime we wanted to eat early we made reservations. I would make them, rather be safe than sorry.
We were able to get in without reservations right when they opened (7:00 a.m.) last July. They do get pretty busy later in the morning, so if you want to eat at peak breakfast time, I'd try an ADR just to be sure.
Probably safe to make them. But we eat at Kona for breakfast each and every trip. Never made ADR's, only had to wait a few minutes a couple of times. We usually eat there around 8:30 or so..