ridge cap and insulation

Hello, I have a building that is framed with 2x4 and metal on sides and roof. I have 1 problem and 1 question for ya'll ... The problem is leaves and such blowing in through the ridge (that's the top, right?); resulting in debris on the floor right down the midlle of the building. So, is it possible to seal this, and how best to do it; thinking it might be safer (but not feasible) to do this from the inside? The question is about insulation. Right now from the inside I see 2x4 rafter and the bottom of the metal roof. Is paper-face fiberglass suitable? That's it for now, and Thanks much for your expertise and advice! Don C.