Do the sons from a previous marriage become mahram to the daughters of the second marriage?

Q: In the Hanafi Madhab, a man has 2 sons and 1 daughter from his previous marriage. He divorces their mother and marries a woman which he then has 2 daughters with.

1. Do the sons from the previous marriage become mahram to the 2 daughters of the 2nd marriage?

2. Do the sons qualify to be mahram to their step mother?

Reading the Yusuf Ali translation of the Quraan

Q: I would like to ask a question regarding the Yusuf Ali translation of the Quraan. I heard in a lecture that Yusuf Ali was unable to speak the Arabic language as well as the fact that they say his version is incorrect.

I also read the same facts online. Can I continue reading this version as I have always done so. Or could you advise me on what is the best translation of the Holy Quraan I could find.