Questions regarding parenthetical citations

Hi, everyone! I just joined this community and I'm wondering if anyone can help me with parenthetical citations.

I understand the basic rules, but I have a couple questions.
What do I cite when my information is from an article from a website that does not have an author or a date?
Some article titles are very long; should I put the entire title?
If I restate something I said earlier in the essay that was already properly referenced, should I reference it again?
Thanks!

If you use information from an article that does not have an author or date of publish, you do not have to list them. You just cite what every is available to you.

I'm not sure if you can shorten an article title in a work cited. I don't think so. However, when you cited a source, you just type the first few words. ex. article title is "A New Discovery Leads to Development of A More Efficient Engine" You would cited it in a paper as ("A New") You only need to type enough words to distinguish a source from others. If there was three articles that start with "A New" then you would add more words ("A New Discovery").

Yes, You have to reference stuff you use in another part of the essay. Although remember that redundancy should not be allow in an essay. Assume that if you stated a detail before in an essay, you don't have to remind the reader.