Icons and pictures of animate objects on mobile phones

Q: In mobile phones there are pictures in menus that we cannot delete, e.g. my contact list has the symbol of the silhouette of a human head. When we use messenger there is an icon with a smiley face displayed all the time. When you click it you can choose images you want to insert. This smiley icon is always displayed on the messenger screen. You cannot get rid of it. Can we still use the messenger, knowing we will use phrases like insha Allah etc. so Allah's Name would be displayed on the same screen as the smiley icon?

Responding to the call of Nabi (Sallallahu Alayhi Wasallam) even if one was engaged in Salaah

Q: A family member recently heard a lecture in which the speaker made a comment that if you do not think of nabi salaalaahu alaihi wa sallam in your namaaz, your namaaz is invalid. The speaker furhter presented a hadith as his proof in which he only mentioned that a sahaabi was performing namaaz when Nabi (Alaihis Salaam) called him and he failed to reply.

Is there any such hadeeth, if yes, what is the complete hadith with the explanation?

Hoors of Jannah

Q: My sister-in-law is a revert. She accepted Islam but because she can't accept that in jannat the males will have many hoors to have relations with so now she feels that this is injustice and she wants to go back to christianity! If mufti sahb can please advise on how to remedy the situation.