Blue smoke is usually valve stem seals. White could indicate there is a small amount of coolant leaking into a cylinder. Did head gaskets on a Northstar for the same reason but had a small misfire on startups and an internal coolant leak.
A puff of steam on start up is perfectly normal. When you shut your truck off the exhaust is full of warm moist air. As it cools while parked that moisture condenses and falls out of the air and settles in the bottom of the exhaust system as small amounts of water. When you start the truck up that water is reheated and exits as steam. In cold climates that steam will continue until all the water is reheated and expelled. In warmer climates you won't notice it for as long.
Pretty much if you can see your breathe, you'll see steam.