no
bowl
The particles emitted by a radioactive substance can change other atoms, and in some cases, they will turn into radioactive isotopes.
This phenomenon is rare, non obligatory. For example beryllium irradiated with alpha particles from radium emit neutrons.
When food is placed inside the microwave oven, the microwave released will 'agitate' the water molecules in the food, which causes heat to be produced, which then cooks the food.
nothing
5 minutes in glass pan
Radioactive materials emit dangerous radiation; most of this will be blocked by a box of lead.
A typical paper clip will cause a small "short" in the microwave energy inside the oven, but likely will cause no harm. Metal of any sort can become hot because of the RF currents that will travel through it and possibly cause a fire if there are flamable items in contact with it.
Bone Scan
Answers.com says it is a microwave amplifier in which a Gunn oscillator functions as a negative-resistance amplifier when placed across the terminals of a microwave source.
Americium is an artificial metal, solid, radioactive, placed in the actinoids family.
This phenomenon is not mandatory.