Did the wives of the prophet (SAW) receive the same mahr and nikah walima. was it sunnah to have nikah and walimah at the same or two different parties? If husband takes second wife should he treat second wedding arrangements as given to the first?

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

It is proved that the Mahr of the Prophet (Sallallahu Alaihi wa Sallam) (money paid by a husband to his wife on the occasion of marriage) to his wives was 12.5 Awkeias of silver (each one equals 40 Dirhams).
It was reported from Abu Salama that when he asked Aisha about Allah's Messenger's (SAW) Mahr, she said: "His Mahr to his wives was 12 Awkeias and one "Nash" and she added: 'Do you know what is the Nash'. The answer was in negation. Aisha said: 'one half of Awkeia'. So, all will be 500 Dirhams (i.e. about 1490, grams of silver)."
Al-Tirmizi reported from Umar Ibn al-Khattab (RAA) that he (Umar) said: 'I have no knowledge that Allah's messenger (SAW) got married to any of his wives or married any one of his daughters for a Mahr exceeding 12 Aukeias'. And Umar did not mention the fraction, i.e. 0.5. According to some narration Umm Habiba's Mahr was 4000 Dirhams. For sure, that Mahr was paid by Negus, the ruler of Abyssinia, on behalf of Allah's Messenger (SAW).
As for Walima (banquet of marriage), it is proved that Allah's Messenger (SAW) gave banquets to all his wives. But, there was difference between them (i.e. concerning walima). He gave walima for some wife with one sheep; others with two Mudds (measure about 543 grams).
It is recorded in al-Bukhari from Thabit from Anas (while they were talking about Zainab's marriage, who said: I did not see that the Prophet (Sallallahu Alaihi wa Sallam) gave banquet for any of his wives as done for Zainab Bint Jahsh. He gave a banquet for her with one sheep."
Another Hadith in al-Bukhari from Safiya Bint Shaiba reads: "The Prophet (Sallallahu Alaihi wa Sallam) gave a banquet for some of his wife with two Mudds of barley."
We think that such a difference was due to the Prophet's financial state.
As for specifying the time of Walima, there is disagreement among scholars in this concern. Ibn Hajar said: 'There was disagreement on this issue among al-Salaf, if Walima should be done the time of the contract or after it, after consummating the marriage with the wife or after that, or if is with a prolonged time starting from the contract till consummating the marriage with the wife.' For sure, there are many opinions. There is no hard and fast rule in this concern. Some scholars said: 'Walim should be after consummating the marriage with the wife. This Walimah is sunnah for one time, and there is no harm if it is done again, and this is the opinion of Ibn Qudamah , who legalizes making the Walima, for more than one day.
As for spending on the arrangements of marriage with the second wife, we state it is not obligatory to do with the second wife as you did with the first, i.e. concerning Mahr, donation, Walima and so on.
Ib Hajar , while commenting on the above-mentioned Hadith reported by Thabit said: Ibn al-Muneer said that 'since there is some preference to one wife over the other concerning walima, it becomes legal to give some wife a special present and so on.'
Allah knows best.