Galvanized fasteners into exterior concrete - good enough for 20+ years? Or stainless?
My first deck, years and years ago, I used galvanized lag bolts and they corroded after about 7 years. My next one I used the best deck screws available, guaranteed for the life of the deck, etc. When I had to replace a plank after 4 years, the screws were rusted and snapped off when I tried to remove them. The corrosion in both cases really hastened the rotting of the wood. My next deck I used all stainless steel screws and they have held up great. I replaced a plank after 5 years due to warping and when I removed the screws, they looked like new. There was no rotting around the screw holes either. I'd use stainless screws for the wood to wood and stainless lag screws and lag shields for the wood to concrete. Make sure you get lumber that's meant to be in contact with the ground or concrete.