1. It easy, but a little complicate to explain:
First: The 2 boy cross the river.
Second: One of the boys returns to the beginning with the boat.
Third: The adult cross the river.
Forth: The another boy returns to the begging.
Finally, the 2 boys cross for last time the river.
2. No idea what do you mean.
3. If SGW meaning Star Wars Galactic: I had to search by google to undertand this. :$
4. Assuming that his combined speed don't exceeds the light's speed, same as Max.
5. That one is for Niet ...