While there a very limited options for unskilled work and local wages are very low, teaching English or other language tutoring is an option.
Avoid paying for volunteering. Simply contact a bunch of NGOs and let them know you are interested in working for them. Sometimes you can also get a paid job after doing some volunteer work. Just be clear that you are able to stay a fixed amount of time for unpaid work, and that you would need some money to continue your work.
Peruvian Spanish, particularly in the Sierra and jungle, is pronounced much less clearly than European Spanish and Spanish from other Latin American countries, especially Mexico, Colombia and Chile. People don't tend to speak too fast, although in coastal areas, especially Lima, people speak considerably faster than in other areas, and they also use slang quite liberally. On the whole, Peru is a good and cheap place to embark on Spanish courses once you are there.
Some slang terms:
chévere, bacán, cool.
chela Cerveza, a beer.
Me da cólera, Me llega, it pisses me off.
Ya, right, sure sometimes "ok" or "yup".
Loco ,crazy person.Usually said in a friendly manner, also means "mate, friend, buddie"
Tombo, is cop and cops don't like hearing it.
Chiboloa, a kid.
Bamba fake, counterfeit goods & products
Money is often refered to as plata as in silver. Mucha plata = too much money "that's expensive!".
Some slang terms come from Quechua:
Que piña: means 'what bad luck' even though 'piña' in Quechua means 'coraje' or in English 'infuriating'.
Tengo una yaya: means 'I'm injured'. In quechua 'yaya' means injury. And 'yawar' means blood.