To whom does "Vayesapru lo" refer?
Why did the spies add the (otherwise superfluous) words "el ha'Aretz asher Shelachtanu"?
Oznayim la'Torah: It was a slight against Eretz Yisrael - 'the land to which Moshe sent them', intimating that neither they nor K'lal Yisrael had any personal connection to it. 1
See Oznayim la'Torah.
What are the implications of "Eretz Zavas Chalav u'Devash"?
Rashi (13:5): It implies that milk flowed freely from the goats and honey from the dates and the figs.
Seforno: The spies conceded that the land was not only a good land, but that it gave its produce without effort ? including grazing-ground for the cattle and juicy fruits fit for a king. 1
Since the spies intentions were to give a bad report of the land, why did they begin with "ve'Gam Zavas Chalav u'Devash hi"?
Rashi #2 (in Pasuk 23): What they meant to say was 'Just as its fruit is different (exceptionally large), so too are its inhabitants.
Rashi #3 (in Devarim, 1:25 and Yerushalmi, 9:6: It was Yehoshua who declared 've'Gam Zavas Chalav u'Devash hi!", and the other spies who said '"Efes ki Az ha'Am!"
Ramban #1: They said it in reply to what Moshe had said to them "ha'Shemeinah hi Im Razah", and they added "ve'Zeh Piryah", to what he said "ha'Yesh bah Eitz Im Ayin." 3
Ramban #2 and Moshav Zekenim: Refer to 14:3:2:1.