My question was deleted because it was "incomplete", but I'll answer again.
Simple
This sentence is simple because it contains one singular idea. It may be incorrectly identified as compound because the subject is compound (Forest rangers and volunteers). This is an easy mistake.
Hope this helps!! Good luck, mate. :)
I believe it is to warn because the poet is warning their father that if he goes to far, the poet will be lost
Yes, you could use it as a hook. I don’t know about background information and definitely not the thesis.
The best word would be were because it is in the past tense :)