Email etiquette expectations are often surprising to me as well. Everyone has their own pace of replying to emails, and I tend to ascribe too much significance to unexpected delays in response. Also, how you start and end your emails can be terribly important. Some people are offended by casual greetings or off-hand closing words, for instance my father once stopped talking to me for a year over an email that did not begin "Dear Dad" and end "Love, XXXX". Unfortunately I did not even realize that year that he was deliberately ignoring me. So yes, I hope email is a good option for you, but beware that email can be counter-intuitive in some ways as well. I think consistency is a good bet once you know how your friends like to be addressed.