How fast is water transported from roots to leaves?
You can find some answers for your questions in this paper (it is only for Ricinus communis, but you may follow the cited by from google and find for other plants):

http://onlinelibrary.wiley.com/doi/10.1046/j.1365-3040.2001.00704.x/full

velocity in the phloem (0·250 ± 0·004 mm s−1)
xylem in the light (0·401 ± 0·004 mm s−1), in the dark (0·255 ± 0·003 mm s−1)


Graphs on daily change are on the paper.