It's not a Jewish doorbell. It's a home security device called a mezuzah. The software inside this gadget is a scroll with the words beginning, "Hear O Israel, the Lord is our G‑d; the Lord is one"...
Kosher foods are divided into three categories: meat, dairy and pareve. One of the basic principles of kashrut (the laws of kosher) is the total separation of meat and dairy products.
Your home is also defined by its contents. Aside from those who live there, the most significant items are the Torah books lining the shelves and scattered about.
You thought challah refers to the two braided loaves of bread reserved for Shabbat meals? It does, but mainly, challah is the small chunk of dough we tear off and burn...