Almost certainly no.
No
Yes it is.
Anything you want.
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.
no
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.
no but you need java
Try a mod. You could use InvEdit or SPC (Single Player Commands).
No, many people are using minecraft without any problems with viruses.