This page will document any different redstone behaviour than normal vanilla.
Redstone is now waterproof. That means water cannot remove restone dust, tracks, redstone torches, and other things like levers.
Hoppers require dust to stop them. Placing a torch next to them will not work. We know this ruins some redstone builds, however, the fact that there are redstone signs and that hoppers are able to wirelessly transfer items directly to chests and other hoppers will create entirely new and even more complex builds possible.
The Redstone Proximity Sensor is a redstone torch that turns on when a player is near! crafting takes 3 redstone torches in a vertical line in the middle of the crafting table, and right-clicking gives a GUI menu.