Maybe you're not using a pick to mine. You need to use a pick.
To place blocks in minecraft, right click. To destroy them, left click.
You have to right click
Redstone blocks? You need an iron pickaxe.
The Efficiency enchantment makes you mine blocks faster.
Redstone blocks? You need an iron pickaxe.
you cant
yes but you will not be able to mine blocks anymore.
You shift click on the block and place it where you want it
You can use an iron, gold, or pre-existing diamond pickaxe to mine diamond ore or diamond blocks
You need to have the Silk Touch enchantment on your pickaxe, to be able to mine certain blocks instead of destroying them. With Silk Touch you can mine Ice, mine things like Diamond Ore instead of Diamonds, blocks of dirt with grass on already, etc.
Sharpness is one of the enchantments in Minecraft. Each enchantment has a different purpose. In this case, Sharpness decreases the amount of time required to mine a specific block. You can mine compatible blocks at a faster rates.
Yes, Adventure Mode only disables you from placing and destorying blocks. But in 1.4.2 you can mine the blocks with certain tools.