Find a cave or dig one yourself and it will be lower in the depths.
You will need an "upgraded" pick to mine some of the "harder" ores. You can't use a wooden pickaxe to mine diamonds for example as the block will just shatter into nothing.
Redstone acts like a wire you can use it to make doors open and to make minecart tracks and more
You have to mine redstone ore.
Redstone Blocks now exist in Minecraft 1.5. You can make them by combining nine redstone dust on the crafting table.
You get redstone dust and place it on the ground or a block. You can't put redstone wire on walls or roofs.
Make a redstone circuit.
Yes.
You must use a regular track for turns; redstone-powered tracks and pressure tracks cannot support turns in any track (as of 1.5.2).
You mine it from redstone ore.
redstone torch
Redstone is the electricity of Minecraft. Using Redstone, one can make a infinte variety of electrical devices such as arrow traps and blowing up TNT.
To make potions last longer, you add redstone to them.
You need an iron pickaxe to get redstone in Minecraft.