In what cases should I completely state a theorem I'm about to use? This is the question. The theorem is taken from someplace else.
In my case, I want to use the asymmetric case of local lovasz lemma , and I am not sure if I should completely state it, or just refer the reader to (lemma 5.1.1 on pg ..). 

If the answer is yes, the next question is where. Specifically, in the middle of the proof, it is strange to have all of a sudden another lemma. So I guess I should state it before the start of the lemma(should I write: I am about to use this lemma?). 

Thanks.
For my taste, I'd "recall" the precise statement exactly when you need it, in the internals of your proof, as you seem to indicate. I myself have become ever fonder of a math writing style which does not require so much flipping back-and-forth to understand what's being said. (Especially the otherwise-precise quasi-Bourbaki of referring to things by some (necessarily artificial and meaningless) numbering scheme, rather than any sort of descriptive reference.)

In particular, for simply the statement (rather than proof) of a result, adding an appendix would make things harder to read for many people, and the people who already know the result would not gain much. Skipping over known things is easier than flipping back-and-forth.

That is, allowing your readers to read straight through seems to me the ideal. So, no, similarly, don't introduce all the notation at the beginning and then expect people to remember it. Sure, you could have an appendix for reference for notation, but it really should be explained when first used, ... in my opinion. That kind of thing.