No.
All fruits can be cross pollinated within their own family, but unless the fruit is a true Species they will not come true from seed.
Usually you take the tassels off to pollinate corn (you shake the tassels onto the silk) each of the silk hairs produces one kernel of corn. Also, Detasseling is done to cross-breed, or hybridize, two different varieties of corn. Corn is planted in alternating rows of different corn varieties. One variety is detasseled (tassels removed ) and is fertilized by the second variety to produce an improved hybrid.
The seed could be exposed to chemicals or radiation that could cause a mutation. Or the pollen from different types of sunflowers could pollinate different sunflower flowers. Sometimes a virus will mutate a flower.
You detassel field corn to prevent cross-pollination, often from an adjacent field where seed corn is being grown.
Yes. Sunflowers are grown from seed.
You can cross-pollinate various fruits such as apples, pears, cherries, plums, and peaches. These fruits are often compatible for cross-pollination, leading to successful hybrid varieties with desirable traits.
Grow them from seed
Just planting them does not mean the will cross pollinate. Most citrus plants are self-fertile and also if cross pollination should occur with citrus, it's possible the seeds would be affected and when those seed are planted, they may or may not produce fruit with a taste that differs from the parent plant.
All sunflower seeds contain oil. Oil seed sunflowers will have the most amount of oil per seed.
As the seed that you eat
No, they are seed producing.
Yes, sunflowers can self-seed and spread on their own through the dispersal of their seeds by wind, animals, or other means.