It’s pretty unusual for juniors or seniors to live in the sorority house (on big campuses) unless they are officers. The houses just don’t have enough room so usually sophomores and officers live in the houses and the others live off campus, sometimes together, sometimes not. I assume you have housing lined up for this year, your junior year, and if you join a house you wouldn’t move in right away (you’re in the dorm?)
Your financial aid package might cover R&B, but only if you live in the dorm. It really depends on what FA is covering that R&B. If it is a Pell grant, or loan, then yes, you can use it for off campus housing. My daughter had an athletic scholarship that would have covered R&B, but only on campus. She wanted to live off campus, so she had to pay her own rent.