What is the halachic difference between a yad and a shomer with regard to being counted as part of the food?
Halacha 1 states that a yad is susceptible to impurity and imparts impurity but is NOT considered part of the food. A shomer IS considered part of the food, so it is counted with the food for volume purposes.
Question 2
Why is there no concept of yadot when harvesting grapes for a winepress?
Halacha 5 explains that when harvesting for a winepress, the person has no need of the stem (it would absorb liquid), so it is not considered a yad.
Question 3
What is the status of the middle peel of an onion when it is cut?
Halacha 10 states that for the middle peel of an onion: when whole, it is combined with the food; when cut, it is not combined.
Question 4
What is the status of olive and date seeds, even if they were cooked with the intent to eat them?
Halacha 16 explicitly states: 'Even if olive and date seeds were cooked to be eaten they are not susceptible to impurity.'
Question 5
When are the roots of garlic combined with the food for impurity purposes?
Halacha 18 states that the roots of garlic, onions, and leek when they are fresh are combined with the food. Halacha 19 states that when they are dry, they are NOT combined with the food.