3) I would like to bounce JUNK mail back to it's sender like I could do in Apple Mail. Is it possible? How would I do it?
You can't with Entourage, and you shouldn't.
Virtually all junk mail comes from forged addresses either ones that point nowhere, in which case your bounce messages don't achieve anything except to add to the bandwidth of your ISP (and so increase their costs and ultimately yours); or real addresses that have been spoofed, in which case your bounces are going to some unwitting innocent victim of the spammer.
Just think about it spammers send out millions of mails every day, a reasonable percentage of their email addresses will be dead and generate a bounce. They don't want to deal with these bounce messages coming back in their thousands, so they arrange their end of things so they never see them. They certainly don't take any action over the bounces, the whole point of spamming is that it is a very near to zero cost marketing tool with a minuscule return. The only way the spammers make money is by not investing additional time and cost in maintaining the system. It costs them just about nothing to send mail out to 10% bad addresses. It would cost them a serious amount of management time to remove those bad addresses from their mailing lists based on the bounces they could receive the economics don't add up, so they avoid the bounces and keep on sending.
