1. Just take a piece and put it on top of a bowl filled with weed. Keep the flam directly on the opium to make sure it burns. Then, just smoke liek regular. You'll know it's hitting because it releases a really sweet smell, like incense. It tastes sweet, too.

2. A piece the size of a small peal- about 1/4" in diameter is plenty.

3. $10-$15 per gram is good. Due to the relative scarcity of opium, particularly in light of erdication efforts in Afghanistan, you may see higher prices. As far as eyeballing it, it's hard to say since the opium could come rolled up in a ball or mooshed out flat or something in between. Just go buy a cheap hand scale.

A word of caution about opium: IT IS HIGHLY ADDICTIVE. Opium is the precursor to heroin and I hope you know the addictive qualities of heroin. If not, watch trainspotting. Opium is what really screwed up thousands of people in China when Britain introduced it there solely to destabilize the country and make it more open to British trade and influence. It almost destroyed China. In light of its contemporary history, fuck China. Whoops, a rant!