A Romanian deadlift is known more descriptively as a stiff-legged deadlift. It's done from the floor like normal but instead of crouching down to start it's done from a straight legged standing position.
A rack pull is a deadlift done normally (legs bent) but the weight is pulled off of a rack instead of the floor. The range of motion is less, which allows you to work with more weight.
I do my dips with my hands spaced at exactly the width of the dip tower. Any less, or more, and I think I would fall down.