With regards to verse 19:67 it would appear that what we are dealing with is a bad interpretation of the verse. Moiz Amjad has translated it (in an article dealing with this exact subject, which you might want to
read for further clarification on this): "Does not man call to mind that We created him [while] before that he was nothing." Meaning that doesn't man call to mind that before there was no man and God then created him, not that man was created from nothing. When we look at the precedeeding verse it becomes more apparent that this is what the verse means.
"And says man: When I am dead, shall I truly be brought forth alive?" Qur'an 19:66
This verse shows that man is questioning whether or not the ressurection will take place. The next verse, 19:67, is God's reply to man, in which God affirms that He had the power to create man before when there was no exsiting man, and so why shouldn't God have the power to bring man back to life. Let me provide some more translations of this verse that are a little more clear as to what it means.
"Does not man remember that We created him before, when he was nothing?" (Maulana Muhammad Ali)
"Doth not man remember that We created him before, when he was naught?" (Pickthal)
Again we can see from these translations that the verse says that God created man (not specifying what from) when there was no man before.
Now, regarding verse 52:35 which states:
"Were they created of nothing, or were they themselves the creators?"
Firstly, this verse doesn't state that God created man out of nothing, in fact it's asking the disbelievers if they were created out of nothing. So it doesn't support your idea. Second, there is a greater meaning to it as can be seen if one reads the commentary provided by Yusuf Ali, which says:
"Three possible alternative meanings are suggested by the Commentators, according to the meaning we give to the Arabic preposition
min = of, by, with, for. (1) Were they created by nothing? Did they come into existence of themselves? Was it a mere chance that they came into being? (2) Were they created as men out of nothing? Was there not a wonderful seed, from which their material growth can be traced, as the handiwork of a wise and wonderful Creator? Must they not then seek His Will? (3) Were they created for nothing, to no purpose? If they were created for a purpose, must they not try to learn that purpose by understanding God's Revelation?"
It seems to me that (3) is probably the most likely meaning because Maulana Muhammad Ali has stated the same thing.
His translation of the verse:
"Or were they created without a (creative) agency? Or are they the creators?"
His commentary says:
"Or without a cause, or without a purpose."
As for the "We" that is used throughout the Qur'an, this has been discussed a number of times on this site. It is merely a "Royal We" refering to one entity and not a number of entities. For more clarification go
here, and remember that the same type of thing exsists in the Old Testament as discussed
here (my post on page two discusses it with regards to the Qur'an).