DECK, CONCRETE AND PATIO PAINTING

1: DECK Frazee recommended for a deck "The best product would be "deck and dock" it will last and hold up to foot traffic. A cheaper option would be 203 duratec.It will work but is not designed for foot traffic and wont last as long.

2: CONCRETE PAINTING 
Hi, from my experience moisture is the main cause of paint peeling on a horizontal surface. 
From the pictures it looks like the original paint never soaked into the concrete when it was first applied. I always recommend reducing the first coat of paint with water. By adding 25% water to the first coat of paint it allows it to soak deeper into the concrete rather than just sitting on top of it. After applying the first reduced coat, let it dry then add a second coat of un-reduced paint (no water added)