Whenever you refer to a study that was performed in the past, you should use the past tense. This includes the literature review, but also your OWN study, because your study was also performed in the past and you are now reporting on it. "The following research questions guided this study..."
If your talking about your manuscript, separate from your study, present tense is appropriate. "This section presents the findings of the study."
I invite you to look at my document linked below, which may give you additional ideas about organization of your research paper.
Conference Paper Research Study Manuscript Outline