The sefer Chalav U'Dvash answers that Hashem's presence is constant. It is a person's perception of Hashem's presence which changes. Hashem’s appearance was caused by Avraham’s piety. Therefore, we can consider Avraham as doer of the action and his name is referenced first. (Itturei Torah)

Chesed (kindness) for Avraham was something that he actively pursued. It did not result from merely a reaction to seeing other people suffer. If there were no guests to be had, he felt compelled to run out and find some. Chesed was Avraham's very being and the essence of his service of Hashem. This is why Avraham felt it was so important to pursue guests and hospitality, even during the moments when he stood before the Divine Presence. He viewed these guests as a chance to develop his inner soul, the essence of which was chesed. That is why the hospitality of Avraham was so special. He realized that this was G-d’s will and he didn't waste any opportunity
(Michtav M'Eliyahu)

Chazal say that when Lot invited the angels into his home, his wife did not participate in his act of hospitality, which was against the law in the wicked city of Sedom. Instead, she asked her neighbors "Who has salt for my guests," thereby publicizing that they had visitors. Soon thereafter, all the townspeople gathered around the home and demanded that the visitors be handed over to them.

She now got the fitting punishment of being turned to salt. But, why did the punishment occur now, when she looked back?

The words "after him" are meant to refer to the time when Lot would no longer be living and she would be a widow. Now that they had lost all of their worldly belongings in the destruction of Sedom, even though her life was being spared and they were running for their life, her thoughts turned to her property. The concern about property at this time of crisis aroused judgement in Heaven. She was found lacking in generosity. She failed to demonstrate good use of worldly goods and that is why she received her punishment now. (Kli Yakar)