1) What would you do if someone approaches you from behind when it is dark out and you are walking alone? If you do not rely on the sound of them coming up behind you, is there another way you stay aware of your surroundings when light is limited?
Even when it's not dark I often check behind me. People are always forgeting "one more thing" they wanted to tell me, so looking back is habit. I'm a certified personal protection instructor and a bee-keeper who works at night without lights loading and unloading beehives. Even in the blackest night there's some vision once eyes become accustomed. I'm at home and confident in the dark--an aggressor would soon find himself a victim.
2) I understand that deaf people still have voices and can use them at their will, but are deaf people taught to yell and scream in a kidnapping situation like hearing people are? If not, how would a deaf person handle an attempted kidnapping?
I speak (often way too loudly) so I have no problem in that area. My sis is deaf since birth but can (and does) scream bloody murder when scared. Besides, a kidnapper would quickly bring her back and offer me large sums of money to take her.
3) What is the best way to handle if you are lost in nature and cannot hear wild animals approaching or a search party calling for you?
You do the same thing a hearing person should do--you make lots of noise in the woods to avoid surprising wild animals. The best noise makers are BIG sticks to knock together and against trees. Any self-respecting bear or mountain lion will find reason to be in the next county, and searchers will more likely hear you. But don't forget visuals like bright fire at night and smoking fire during the day.
4) Are deaf people allowed to be lifeguards?
Absolutely.
5) Do deaf people avoid playing games that require blindfolds?
Are handcuffs involved, too? Oh, you mean parlor games. No, giving away two senses is too much disadvantage.