Q2. "[I] am trying to find out if presidential elections are held during war?"
There is nothing in the Constitution that addresses this question directly, which essentially means that elections must be held as spelled out elsewhere (Article 1, Section 2, Article 1, Section 3, Article 1, Section 4, Article 2, Section 1, and Amendment 17). We can also look at history and see that elections have been held many times during wars, both declared and undeclared: 1812 (War of 1812); 1864 (Civil War); 1900 (Philippine-American War); 1944 (World War II); 1952 (Korean War); 1964, 1968, 1972 (Vietnam War); 2004 (Second Gulf War). A list of all election results is available at this site.