Your question mainly concerns the usage of modal 'will'.
The thing is that Future Perfect, as you call it, is rather rarely used to denote the result of some action in the Future but is frequently used in the literary style as an anticipation of the result of an action in the Present, say:
"He looks happy. He will have passed the test".
Again, of course it can be used to refer the result to the Future... in some cases, as in: "I'm sure he will have done the homework by 6, and we can go for a walk together."
...I don't remember if I have ever seen sentences like that, though...
If it helps,