陰 is in the 常用 kanji list, while the other is not. It looks like an old form that some people still use.
Did anyone notice the examples use 2 different kanji? Which one is the right one? 陰 or 蔭 ?
I have heard it used in negative situations as well, although this site is for JLPT preperation. the ultimate goal should be to learn Japanese. Classroom Japanese is far from the real thing. keep that in mind while you study and you might improve faster than you had expected.
普通はよい結果になる場合に使うが、皮肉な表現として、悪い結果になる場合にも使うことがある。 This is written in my JLPT2 book, so bamboo4 is right.
PaulO is correct. おかげで is used in positive connotations, such as "thanks to...". While せいで is used in negative connotations, usually to express blame, such as "because of...". And I agree that these examples should be groomed according to grammar level. However, exceptions can be noted if the context/situation is properly explained.
On the contrary, お陰で can be used in a negative sense in many situations, e.g., お前さんのお陰で大変な損をしたよ. I don't personally care a hoot about JLPT or whatever - when you have to learn, you have to learn.
Hang on bamboo4, In all of the textbooks I've read, お陰で can only be used to indicate a positive outcome in JLPT2. It may be used in other contexts (maybe to express irony in colloquial Japanese) but for JLPT2, I don't think your example is valid. I think you mean 〜のせいで.
hither and thither あちらこちらに
The second example is to show that this expression can be used in a reverse situation.