Without constructing a full itinerary for you, some worthwhile stops on the coast road (with slight detours) are:

Newcastle

Hunter Valley (if you like wine)

Port Stephens (slight detour)

Coffs Harbour (and hinterland including Bellingen and Dorrigo)

Yamba

Byron Bay and Hinterland (Byron Bay itself is a bit touristy and can be a bit “backpacker”)

Kingscliff/Casuarina/Murwillumbah/Brunswick Heads

Guess you’ll have to spend some time on the Gold Coast

Re food: There’s lots of fishermans’ co-operatives that will sell good, freshly caught seafood and cook it

In Coffs, I recommend Seasalt Seafoods (in Coffs or Sawtell) and Fiasco for good Italian

Just outside Murwillumbah is Tweed River House which is excellent.

Perhaps come up with an itinerary and we can comment on it.