Yes
You craft a ladder in Minecraft by filling the Crafting Table grid full of sticks except for the top middle and bottom middle slots.
All you have to do is go to the ladder, then press nothing, and your character will go down.
Yes
YEP.
Make a full size letter H in the crafting table using sticks.
A ladder should be place at 1m form the base of the scaffold .
This is not the place to find out about Minecraft. Look at the Minecraft Wiki to find out about the game in general.
There is no other LEGAL place to buy Minecraft.
The best place to look is on the minecraft forums
Place the world in your minecraft bin's saves folder.
same place as everywhere else from the minecraft website