I was based in christcurch all last year and did nothign but boulder up there so...
1) Can range from perfect mid teens temps with clear blue skies and no wind to thunder and snow storms. Generally though its the best time of year to be climbign there, the friction is near its best (winter is better) and the weather is more settled than spring.
2) Three guides i know of - rock deluxe (doesnt cover flock), The spittle hill only guide, comprehensive guide including flock that to my knowldege isnt complete yet.
If you've never been there before just go and climb and dont worry about the grades as your ego is likely to take a beating due to the unique nature of the bouldering. If you will need a guide my vote is for rock deluxe, covers all the good stuff in quantum and spittle plus climbing if your into that :-) Then just ask locals for flock info in town/ cragieburn.
If you want any further info or must ticks etc just ask. Alrob and Mousey have a fair breadth of knowledge about the place as well.