Thank you for an excellent question, Hannah. As ever is used to describe a situation, behavior, etc. that remains the same as always. “Miss Smith, prompt as ever, arrived on time.” “The bakeries meringue pies were as perfect as ever.” Ever since is used to describe a point in time exactly and to describe a situation, behavior, etc. that has existed since that point in time. “Ever since Junko met Alberto, she knew he was the man she wanted to marry.” “Ever since last year when they hired a new chef, the restaurant’s food quality has declined.” Please let me know if you have any questions. Andrea Edes, teacher.

"Have you ever......" example: "Have you ever smoked" or "have you ever eaten cake" means have you done it before in your lifetime "Ever since...." example: "ever since the argument with my sister i didnt like her" or "i was sick from alcohol and ever since then i have not drunk it." This means you are reffering to a previous event that has made you change your opinion on something "As ever" - we dont really use in england much. We would say "as usual" instead. Example: "my sister is being annoying, as usual" it means the persons behaviour is nothing unusual they are acting how they always act.

'as ever' = used for saying that someone’s behaviour or a situation is the same as usual, or the same as it has always been. Example 1: Gordon, as ever, tried to make difficulties. Example 2: caravan holidays remain as popular as ever. 'ever since' = continually or often from a past time until now. Example 3: We both liked the idea and have been working on it ever since. 'ever since' = continually from the time in the past when : since. Example 4: She's wanted to be a firefighter ever since she was a young girl. In short, as I understood, 'as ever' is used in Simple Tense, but 'ever since' is used in Perfect Tense. Upd: I hope, it will be helpful for you, Hannah. https://www.englishforums.com/English/AdverbEver/pcxzv/post.htm

You can ask something like "Have you ever smoke?" if you want to emphasize that you didn't mean any certain date, month or year, instead you just interested has that person ever smoked in his/her entire life. But it's just as far as I know, I'm not a native speaker

http://www.bbc.co.uk/worldservice/learningenglish/grammar/learnit/learnitv352.shtml Try this link.