Virtues of reciting Surah Hashr

Q: Surah Hashr - The Messenger of Allah (sallallahu alaihi wasallam) said: Whoever recites Surah Hashr then none from among Paradise, Hell, Arsh (Allah’s Throne) Chair, Curtains, the seven Skies, the Seven earths, space, wind, birds, trees, mountains, Sun, Moon, and angels would miss seeking forgiveness for him and yearning for his safety. If that man dies that day or that night he would die a martyr. 

Is this authentic? Does one have to recite this Surah everyday to get this virtue?

Keep qadha fast of Ramadaan during the first nine days of Zul Hijjah

Q: I missed 10 fasts during Ramadan due to illness. I am recovered now and wish to complete my missed fasts. I planned to keep the 10 during the first days of Zil Hijjah not expecting any additional reward but just as a sense of fasting is more prevalent around me. 

Please advise if this is ok as our local imam in a talk says Fardh and Sunnah cannot be combined! Should I rather wait and fast after or continue in these days? If I do fast, my intention is of my qadha and will I be in sin for keeping these qadha in the auspicious days of Sunnah fasting?