[koomi]

Regarding 4, the split package[1] is the widely accepted standard for splitting lists in various ways and you will likely already have it installed since quite a few packages (142 to be exact) depend on it.

Regarding 5, I have never heard of LazyLists, nor can I find them on Hackage, nor does that name make any sense since normal (:,[]) lists are already as lazy as it gets. (Lazy) ByteStrings are, as the name indicates, more for raw binary data, but can also be used for text . The modern standard for strings is Text[2]. The OverloadedStrings extension makes it considerably easier to work with literals of the differnt string-like types.

Regarding 6, I find documentation in Hackage packages quite good. Your example, Foldable, not only has a decent explanation of each function in the typeclass definition, but there are also good tutorials (e.g. Typeclassopedia[3]) since it is definitely a non-trivial typeclass.

[1] http://hackage.haskell.org/package/split [2] http://hackage.haskell.org/package/text [3] http://www.haskell.org/haskellwiki/Typeclassopedia#Foldable