It depends on the type of flour. Potato flour, alternately called potato starch is fine for Passover. Flour made from the 5 prohibited grains (wheat, oat, spelt, barley, and rye) is not allowed.
Flax seed is kosher for Passover, as long as it is in the form of a seed; if baked into bread then it would not be kosher for Passover (since all forms of leavened bread are not kosher for Passover). However, flax falls within the category of 'kitniyot' and therefore is not eaten by Ashkenazi Jews.
Yes, grape seed oil is kosher for Passover for all groups including Ashkenazim. You would have to check the labeling for a valid Pesach hechsher though.
Flax grows from a flax seed.
It would have to be certified kosher for Passover.
Flax seed is derived from the flax plant (also known as common flax or linseed).
The label has to say "Kosher for Passover"
Yes, only if they are specifically certified kosher for passover. You can find kosher for Passover olives at any Jewish supermarket
It can be, it would require a valid Passover hechsher.
Yes, it can be since it is made from wine, which can be Kosher for passover if created under appropriate supervision. The bottle would require a kosher for Passover hechsher.
If you were able to find corn vinegar that is certified kosher for Passover, it would be kitniyot which means that the majority of Ashkenazi Jews would not use it.
There are kosher food companies that are now making gluten-free products Kosher for Passover and all-year-round. However, something being gluten-free has no bearing on whether or not it is Kosher or Kosher for Passover.
Arugula is an edible leaf and is kosher year round including Passover.
Yes, they must be certified kosher for Passover though.