A controversy has been raised by some Muslims lately about the above questions.
All references in HADITH which I could find after some searching were referring to the Yahood IN THE TIME OF THE PROPHET(sas).
Every reference to 'yahood' in the Qur'an refer to this group in the time of the Prophet (sas), well after the corruption of their deen.
In Tafsir At-Tabry, Mujahid states that in the BEGINNINGS of both of these groups - An-Nasaara and Al-Yahood - there were BELIEVERS:
- حَدَّثَنَا الْقَاسِم , قَالَ : ثنا الْحُسَيْن , قَالَ : حَدَّثَنِي حَجَّاج , عَنْ ابْن جُرَيْجٍ :
قَالَ : قَالَ مُجَاهِد : قَدْ كَانَتْ أَوَائِل الْيَهُود وَالنَّصَارَى عَلَى شَيْء .
Use of الذين هادوا , Apparently Synonmous With يهود
In Baqarah:62, Allah indicates that among the following groups there are believers: believers (Muslims), Yahood, Nasaara and Saabi'een.
إِنَّ الَّذِينَ آمَنُوا وَالَّذِينَ هَادُوا وَالنَّصَارَى وَالصَّابِئِينَ مَنْ آمَنَ بِاللَّهِ وَالْيَوْمِ الْآخِرِ وَعَمِلَ صَالِحًا فَلَهُمْ أَجْرُهُمْ عِنْدَ رَبِّهِمْ وَلَا خَوْفٌ عَلَيْهِمْ وَلَا هُمْ يَحْزَنُونَ (62)
Different tafaasir are reported from the salaf. One applies this to members of those groups who lived to see Muhammad (sas) and believed in him and became Muslim. Another states that among these nations were minorities holding fast to tauhid and upon the fitra and believers. IF such individuals live to see the subsequent messenger from Allah, they would be among those who believe in them and follow them. These two views are clearly not mutually exclusive and jam' (joining) would be the correct course here. In other words, there continued to be some number of individuals upon iman and fitra among the yahood until Isa came and some of such ones became the believers in Isa. Likewise, there continued to be some number of individuals among the nasaara in a similar state (e.g., Waraqa ibn Naufal). Any such who lived to see Muhammad (sas) believed in him and got two rewards.
At-Tabry said:
فَكَانَ إيمَان الْيَهُود أَنَّهُ مَنْ تَمَسّك بِالتَّوْرَاةِ وَسُنَّة مُوسَى حَتَّى جَاءَ عِيسَى , فَلَمَّا جَاءَ عِيسَى كَانَ مَنْ تَمَسَّكَ بِالتَّوْرَاةِ وَأَخَذَ بِسُنَّةِ مُوسَى فَلَمْ يَدَعهَا وَلَمْ يَتْبَع عِيسَى كَانَ هَالِكًا . وَإِيمَان النَّصَارَى أَنَّهُ مَنْ تَمَسَّكَ بِالْإِنْجِيلِ مِنْهُمْ وَشَرَائِع عِيسَى كَانَ مُؤْمِنًا مَقْبُولًا مِنْهُ , حَتَّى جَاءَ مُحَمَّد صَلَّى اللَّه عَلَيْهِ وَسَلَّمَ , فَمَنْ لَمْ يَتْبَع مُحَمَّدًا صَلَّى اللَّه عَلَيْهِ وَسَلَّمَ مِنْهُمْ وَيَدَع مَا كَانَ عَلَيْهِ مِنْ سُنَّة عِيسَى وَالْإِنْجِيل كَانَ هَالِكًا
Note that he is talking about BELIEVERS among the Jews right up to the time of Isa (whoever among them who subsequently believed in Isa or Muhammad, CONTINUED to be believers) and refers to them as YAHOOD.