To get different varieties of apples on the same tree. Keep in mind the variety of apple you graft on the root stock has to be a earlier variety. For example, a red delicious on a gravenstein.
Take a cutting from mature tree and replant it. This is how all commercial apple trees are grown. Seeds from an apple tree will not produce the same flavor of fruit as what the "parent" tree produced.
trees and a shrub
Not necessarily. If you have other plants in your garden (Flowers, shrubs, etc.) you will not need two apple trees. If you have no other plants in your garden, then yes, you will need two apple trees to pollinate.
they need water
apple trees grow in the cold climate and the coconut trees need water for dispersal
White pines don't need to be trimmed. You can trim off lower branches as the trees grow but leave enough branches to support the trees health.
Pears reproduce by seeds contained in the fruit. Some hybrids do not produce true to variety from seeds. The produce these, you need to do a graft or stem cutting.
Apple trees do not grow well in ANY forest. They need sunlight to grow well.
They spread out because they need more chlorophyll
apple trees grow in the cold climate and the coconut trees need water for dispersal
as much as you got
Apple farmers need bees to pollinate their apple trees. Where bees have been eradicated by pesticides, more bees, or hand pollination, are necessary for the trees to bear fruit.