you can install Single Player Commands and there is a freecam option.
no
you have to cyt
Single player commands are needed.
Delete the bin folder in the .minecraft folder, start Minecraft, and it will say that it's updating. Let it update, then install all of the mods over again, but don't install the one(s) that you don't want.
no
no
You get a mod, such a Single Player Commands.
well minecraft 1.2.3 single player is beta so there are no commands hopefully in the next version
install the aether mod
Use //set cobblestone.
do /clear inventory or just /clear