Dear 8pider
Wa alaikum assalam
Please see my responses below to your questions in blue italics.
1."....If ye are in a state of ceremonial impurity, bathe your whole body......" what is the Quranic definition of ceremonial impurity?
The Quran does not intend to 'define' words of its narratives. In that sense, it is not a lexicon or dictionary. The Quran in the main, merely speaks to an audience that would have been familiar with the semantics used by the Quran and the word 'junub' in such a context would have been / is well known to the Arabic language.
The modern practice is supported by ancient sources which understand it as:
"He was, or became, in the state of one who is termed جُنُب; (S, IAth, Mgh, L, Msb, K;) i. e., under the obligation of performing a total ablution, by reason of sexual intercourse and discharge of the semen. (IAth, TA.)" [Edward Lanes].
This understanding is also supported with regards to tayammum (dry ablution) and some of the conditions which make it necessary.
2."....But if ....you cometh from offices of nature, or ye have been in contact with women,..." I understand from here that passing wind doesn't break wudu since its not mentioned in the verse. However, does sleep necessitate wudu....if one had wudu before going to bed, could he simply wake up to perform fajr without wudu considering of course that he has not had sex or gone to the toilet?
Yes you are correct, passing wind has not been explicitly cited by the Quran as an action that invalidates the ablution.
However, some may feel that it is best practice to observe ablution as flatulence may be accompanied by other fecal debris, no matter how insignificant. However in my humble opinion, this remains an inference which is not without challenge. Some may be happy to go the extra mile ‘as best practice’ to ensure what they feel is complete mental and spiritual purity (as opposed to necessarily physical).
With regards 'deep sleep', one can argue that this is a state in which it is possible that a bodily discharge (of any sort) can occur and one may not be conscious of it. Many people do clean their bodily parts after rising from deep sleep (certainly overnight). There is an argument therefore that deeper sleep would necessitate an ablution. Again, it may be a case where 'best practice' has become cemented as 'religious practice.'
3. Is it necessary to have clean clothes to perform swalah?
Invariably yes, if not only because such an emphasis on cleanliness (both physical and spiritual) has been placed by the Quran generally. However, the Quran also shares the following explicit guidance.
007.031
"O Children of Adam! Wear your beautiful apparel (lit. Take your adornment) at every 'masjid' (whenever one prayers at their place of prayer)..."
Also the method of bathing the whole body is outlined in secondary sources....does the Quran have any specifics or does simply bating the whole body suffice
With regards 'bathing' no specific method is stipulated. Most cultures would know what 'ghusl' entails without prescribing a ritualised method. I would not expect the primary audience of the Quran to be any different - the intention being to wash more thoroughly and completely with a view to remove impurities.
I hope this helps, God willing.
Joseph.