For 3/4 hardwood or BB, I would use a #5 or larger. Saw speed is up to you. I tell my students to start with a medium speed. If you are cutting and it’s dragging, turn up the speed. If you can’t stay on the line because the speed is too fast, slow it down. Saw speed is a matter of comfort. Whatever speed is comfortable, is the right speed. Before you start on good wood, practice on scrap wood.