DevDocs corrections part 1

Started reviewing the developer docs, finding lots of things to correct. I'll do more later, but please review this batch first so I know what, if anything, needs to be fixed moving forward - I'm not entirely sure on the markdownish format used.
Pieter gave a good explanation about the overlapping vocabulary here, I agree this case is a bit messy;
http://bitcoin.stackexchange.com/a/5869

Maybe this is another signal that a technical glossary would indeed be useful, as recently suggested on the mailing list: https://groups.google.com/forum/#!topic/bitcoin-documentation/s_mL1syxYoQ