I would use a mod called Too many items too, I have a tutorial for how to install the mod. (See "Sources and related links" below)
Too many items is a ingame inventory editor.
No
Yes it is.
Anything you want.
Almost certainly no.
I don't think you can I'm not sure but I'm pretty sure they would have a download link to an updated INVedit
Invedit. An Inventory editor.
Yes. you can use INVEdit.
You can always use an inventory editor. I use INVedit
Download it from from the Minecraft forum. The link is under "Sources and related links" below this answer.
Try a mod. You could use InvEdit or SPC (Single Player Commands).
It's safe.
if you want items in minecraft the best edit i know is INVedit. download it, open world iventory and edit it. save it to your world next