Change killer’s to killers
The images and captions helps the readers or audience to understand the main idea because it provides a visual content that could support the idea that is being showed or shared to them and the captions could help in distinguishing the images or is set as a support to the images that is being shown to the readers or the audiences.
I would say that this is true, because an autobiography would be considered more of a descriptive text than a persuasive text.
'can take' would be the verb phrase since it includes the verb and the helping verb.