Baby food pouches- available to fill with your own ingredients and reusable. They have a super heavy duty wide ziploc opening for filling and a screw top spout for pouring. Available form Amazon. I think the ones we have a Brezza brand.
I think only you can answer that question. I made my meals at home a few times and measured how much oil I used. After that it was a simple matter of taking X (amount of oil per meal) multiplied by Y (number of that meal I expect to eat) to figure out how much oil to take. On my long trips I think I was using around 1.5-2 ounces/day, which amounted to about 80 ounces of oil brought along.