Rabbi, can you please clarify the practical rules for utensils?
When buying a new pot, pan, knife, cup, or appliance, how do I know if it needs tevilah, a berachah, kashering, or nothing? Does the material matter?
Also, what are the rules for using utensils from non-kosher restaurants or public/shared places, such as forks, plates, cups, microwaves, kettles, or other kitchen equipment? Does it make a difference if the food is hot or cold?
And if I buy or use a secondhand utensil, how do I know if it needs kashering and/or tevilah?
If possible, could you give a simple practical rule to follow for new, used, and public utensils?