Not necessarily, or even usually, the case.
Compare the cost of transporting a bushel of wheat by horseback to train. The train could probably bring the same bushel of wheat 500 times further at the same cost.
Or, compare the cost of growing wheat in Kansas to Hawaii. Per acre, Kansas can produce 5 times as much wheat. Further, Hawaii can produce certain fruits that Kansas cannot, such as pineapple. When we decide where to grow pineapple and wheat, we should look to maximize our production so that everyone can have more of what they want. We can ship wheat to Hawaii from Kansas cheaper than we can grow it there. Likewise, we can ship pineapple to Kansas cheaper than we can grow it there.
Sure, but realize that cheapness isn't necessarily the highest value. If I was trying to be as cheap as possible with my food consumption, I would eat nothing but ramen. But that is not very preferable, so I'll also eat rice, beans, salad, and meat. It may be more expensive, but it is also more satisfactory.
There are limited amount of hours in the week that I can (or am willing) to work. If I spend all my time constructing roads and someone else spends all their time growing vegetables, we will each have more vegetables to eat and more roads to drive on. Such is the advantage of division of labor and trade.
You realize that the "right to save seeds from grown crops" is given up by the farmers who choose to buy Monsanto? And Monsanto's "ownership" of the advanced seed strains is protected by government intellectual property law?
Remember what I said about "letting people figure things out for themselves?"
No individual thing is the answer. At least, not probably. A magic hat that makes infinite amounts of rice pop into existence would go a long way.
Such is already the incentive of the farmers who own the land. Private ownership of the land is how you avoid tragedy of the commons.
Once again, you're not taking into account costs. "Eating more efficiently" is costly; I need to give up more time to make it happen, I need to consume food I might not like, and so on. Why not make applesauce? Probably because, compared to the processes already in use by factories to make applesauce, it wouldn't be cost-effective. In other words, devoting more time to the applesauce production that's already in place, rather than having someone spend their time picking up apples that have fallen to the ground in an apple orchard that isn't geared towards making applesauce, would produce more applesauce. Would you have more applesauce, or less? I think that answers your question.