The Zayd verse is one of the latest interpolations in the Qur'an, and was awkwardly jammed in as part of the fight over Mohammed's status as prophet vis a vis widely circulating traditions about his family and the right of successorship. It is one of three (3!) instances where the Qur'an clearly uses a proper name of a contemporary person, the other two being uses of the name "Mohammed." This is the very last layer of Qur'anic interpolation, interpolations about Mohammed as a specific named prophet and his status as the 'seal' of the prophets with no male children to inherit that lineage (specifically, Surah 33:40). David Powers has written two books about this issue.
http://www.amazon.com/Zayd-Divinations-Rereading-Ancient-Religion/dp/0812246179/ref=sr_1_1?ie=UTF8&qid=1416259685&sr=8-1&keywords=zaydhttp://www.amazon.com/Muhammad-Not-Father-Any-Your/dp/0812221494/ref=la_B002S08188_1_2?s=books&ie=UTF8&qid=1416259698&sr=1-2The verses about guests staying in the house, also appearing in Surah 33:53, are again some of the most late and Mohammedan interpolations in the entire Qur'an. There seems to be some sort of elaborate attempt to justify a particular tradition, surely widely circulating at that time, when it had become very embarrassing or problematic. 33:52 goes as follows:
"Not lawful to you, [O Muhammad], are [any additional] women after [this], nor [is it] for you to exchange them for [other] wives, even if their beauty were to please you, except what your right hand possesses. And ever is Allah , over all things, an Observer."
Okay, so Allah prohibits Mo from marrying any more women. Then 33:53:
"O you who have believed, do not enter the houses of the Prophet except when you are permitted for a meal, without awaiting its readiness. But when you are invited, then enter; and when you have eaten, disperse without seeking to remain for conversation. Indeed, that [behavior] was troubling the Prophet, and he is shy of [dismissing] you. But Allah is not shy of the truth. And when you ask [his wives] for something, ask them from behind a partition. That is purer for your hearts and their hearts. And it is not [conceivable or lawful] for you to harm the Messenger of Allah or to marry his wives after him, ever. Indeed, that would be in the sight of Allah an enormity."
It is very unclear wtf this is all about, except that it seems to be incredibly elaborate argument about the prophet's family circumstances, and family law in general, all to defend the prophet against charges of excess salaciousness and to establish that he is the Seal of the Prophets in the sense that he "is not the father of any of your men." Also there seems to have been bitter battles over defining the prophet's family and its succession. What circulating traditions this was reacting against, we cannot exactly know, but it's likely that there were many stories about Zayd (the beloved) which the composers of Surah 33 were trying to tame and bring within their Mohammed=FinalProphet position, then just one position amongst many.
It's pretty sad that so much of the earliest traditions were lost, not only because it wasn't written down, but because later Muslims (like Bukhari) deliberately jettisoned all but the miniscule fraction of traditions that they encountered (I believe Bukhari says he selected 5,000 hadith out of 600,000 that he reviewed), doubtless rejecting those that now seemed too scandalous, contradictory, or inconsistent with what had emerged as Islam.