By using the scroller on your mouse. Scrolling up makes the selector in your hotbar go up, and scrolling down makes it go left.
Put it in your quickbar and select it so it is in your hand. Hold the right mouse button down to eat it.
You can. Either scroll on your mouse or use the numbers
No. Minecraft is currently avalible only for select moble devices, xbox 360, mac, and pc
You download a texture pack, drag it into your texture pack folder, and then select it through Minecraft.
esc key then select options
the 1 - 9 keys
There are lots of things that make sound in Minecraft, so it could be a number of things.
It is called Minecraft because the primary things you do in Minecraft is, well, mine and craft.
Yes, put Eyes of Ender in your quickbar, you can throw them and they point towards the nearest Stronghold with an End Portal, just like regular survival mode. You must have the 'generate structures' option enabled when you created the map though or there will be no strongholds.
No, though one of the key things about Minecraft is that you learn to teach yourself things... but if all else fails you can check the Minecraft Wiki.
Go to a site called minecraft wiki
You don't exactly buy things in minecraft. You mine, and then you craft things. I'm assuming this isn't an entirely serious question. :)