1. Yes, the article "an" and the letter E, with the stress on the first syllable.
2. Just like the article "an"
3. I've never seen this name before. Ask the mother who dreamed it up. Diane, however, is a common name: die-AN.
4. That's Spanish. In my terrible Spanish pronunciation, it's ha-blow in-GLACE (rhymes with "place"). I'm sure a Spanish speaker will correct me. My lack of Spanish is why I would need to ask if they speak English.