1.) Proxy wars are fought when two countries in conflict use other smaller countries to fight for them and get involved in their problems. an example would be the Korean war or the Vietnam war.
2.) Both NATO and the Warsaw Pact are formed on alliances. A positive would be that both provide security and safety for the parties involved in either NATO or the Warsaw pact. As a whole, countries that appose the Soviet union (NATO) or support it (Warsaw Pact) would be able to fight stronger against the enemy side. A negative would be that upholding both agreements would be very expensive.
(im not super sure about that negative.)