Volume 8, Book 82, Number 828:
Abu Bakr came to towards me and struck me violently with his fist and said, "You have detained the people because of your necklace." But I remained motionless as if I was dead lest I should awake Allah's Apostle although that hit was very painful.
The term used is the trisyllabic verb w-j-' or waja'a, yaji'u. It means to jab or poke. Not hit, not beat. Jab or poke, like a one year-old jabs or pokes his mummy in the cheek.
As for the issue of Sayyidina Umar attacking Sayyidina Fatima, then know that it is false.
Secondly Tabari doesnot mention this at all, but states : "Take his sword and hit the rocks with it."
-- When Abu Bakr received the pledges of allegiance after the Messenger of Allah, Ali and Zubayr used to enter the presence of Fatima the daughter of the Messenger of Allah and consult with her and hesitate in their allegiance. When news of this reached Umar, he came out until he entered Fatima's presence and said: "Daughter of the Messenger of Allah, none in all creation was more dearly beloved to me than your father, and none is more beloved to us after him than you. However, by Allah, this shall not prevent me, if that group gathers in your house, to order that their door be set afire!" When Umar went out, they came and she said: "Do do you know that Umar came to me and swore by Allah that if you were to come back, he shall surely burn the door with you inside! By Allah, he shall certainly fulfill what he swore, so go away in peace, flee from your opinion, and do not come back to see me." They left her and did not return to see her until they pledged their allegiance to Abu Bakr.
This hadith is Sahih.
And note that Musa - peace be upon him- is Infallible.
When Fatima fell sick Abu Bakr Siddiq came and asked permission to see her. Ali said: "Fatima, here is Abu Bakr asking permission to see you." She said: "Would you like me to give him permission?"  He said yes, whereupon she gave him permission. He entered to see her, seeking her good pleasure, and said: "By Allah! I did not leave my house, property, family, and tribe except to please Allah, and to please His Prophet, and to please you, the People of the House (ahl al bayt)! He continued to seek her good pleasure until she was pleased." 
 Al-Dhahabi said in the Siyar (Al Arna'ut ed. 2:121): "She applied the Sunna by not giving permission to anyone to enter her husbands house except by his command."
 Bayhaqi in al Sunan al Kubra (6:300-301) and Dala'il al-Nubuwwa (7:273-281) who said: "It is narrated with a fair (hasan) chain." Muhibb al Din al-Tabari cited it in al Riyad Al Nadira (2:96-97 #534) and Dhahabi in the Siyar (Ibid). Ibn Kathir states it as Sahih in his Al Bidayah and Ibn Hajar in his Fath Al Bari.