Question: It appears Jason has upsized his shack in this version. He now lives in an abandoned house instead of a rundown shack we see in Part 2. Plus the house has an extensive tunnel system. Finally, where does the electric bill get sent?
Answer: It's possible that he has a generator.
Where did he get the generator from? Home Depot?
Question: In the beginning, Richy gets his foot caught in a bear trap. Did Jason put this there or did the people put it there?
Chosen answer: It was left by hunters. Jason doesn't have the mental capacity to set traps for his victims.
Jason had set up an elaborate warning trip wire that rang bells at his house. I am sure he could have set a bear trap.
I agree. Jason has shown to be quite intelligent and even able to carefully plan his attacks so setting up a bear trap wouldn't be hard to do.
Question: How could Whitney have lived at Jason's underground hideout for 6 weeks without food?
Chosen answer: When Jason brought her brother's backpack, you can see a small table next to the mattress with some bottles and cans, there is also something what looks like bag of chips (or maybe marshmallows?). I'm sure that he knew that she needs food, and brought her something from campers or cabins.
Answer: It's the former summer camp. I would believe they had a generator or two.