LSU doesn't grade on a weighted scale. Your unweighted GPA is a little low for an OOS. LSU does accepts students that have a 3.0 GPA, however, you may not that great of great scholarship money unless you have awesome test scores.
However, if you make straight A's that GPA will rise.
Your ECs are good. That might balance out the 3.1 GPA.
Defintely take the ACT. LSU accepts both SAT and ACT, but b/c most of the students who go to LSU are in-state and all LA high schools offers the ACT; they favor the ACT.
LSU's minimum requirement for SAT is 1030 or ACT score of a 22. Also: LSU requires a minimum ACT English sub-score of 18 or SAT critical reading score of 450, and a minimum ACT math sub-score of 19 or SAT math score of 460.
As for the Honors College, you have to make a 28 on the ACT or a 2160 SAT. http://www.lsu.edu/paurec/freshman.shtml