When books say to read the last Ayaats of Sura Baqarah, is it 2 Ayahs? Or is it 3 Ayaahs? Or does it depend on the Hadith and situation? Do scholars differ in their opinion?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

The last verses of Chapter Al-Baqarah [Quran 2] are the two last verses as the Sunnah clarified. It is confirmed that the Prophet said: “If somebody recites the last two verses of Chapter Al-Baqarah at night, that will be sufficient for him.” [Al-Bukhari and Muslim] These verses are verses number 285 and 286 which mean: "The Messenger has believed in what was revealed to him from his Lord and [so have] the believers. All of them have believed in Allaah and His angels and His books and His messengers, [saying],” We make no distinction between any of His messengers.” And they say, “We hear and we obey. [We seek] Your forgiveness, our Lord, and to You is the [final] destination.” Allaah does not charge a soul except [with that within] its capacity. It will have [the consequence of] what [good] it has gained, and it will bear [the consequence of] what [evil] it has earned. “Our Lord, do not impose blame upon us if we have forgotten or erred. Our Lord, and lay not upon us a burden like that which You laid upon those before us. Our Lord, and burden us not with that which we have no ability to bear. And pardon us; and forgive us; and have mercy upon us. You are our protector, so give us victory over the disbelieving people.” [Quran 2:285-286] as clarified by Al-Mubarak Poori in his commentary on “Sunan At-Tirmithi”.

Moreover, An-Nawawi entitled a chapter of his commentary on “Saheeh Muslim” as: “Urging people to recite the last two verses of Al-Baqarah” and he mentioned a number of Ahadeeth, among which is the Hadeeth narrated by ‘Abdullaah Ibn Mas’ood that the Prophet was given on the night of Israa’ (Prophet’s night journey to Jerusalem and his ascension to the seventh heaven) three things: “He was given the five daily obligatory prayers, he was given the last verses of Chapter Al-Baqarah, and the one who does not associate anything with Allaah from his nation, his great sins will be forgiven.”

As regards your question about the differences of opinion, if you mean whether or not there are difference of opinion in regard to the last verses of Chapter Al-Baqarah, then we have not come across any difference of opinion in this regard in the books that we have at hand.