Starting in spring of 2000 I'm going to stop asking students to read section 2.9. There are no positive or negative vectors. There are no graphs in this chapter with time axes. A brick dropped from a foot off the ground may spend an extra zillionth of a second in the air because of air resistance. Probably, but it all depends on how accurately you want to know the motion of the rock.
Weight is a force, and it has a direction.
Mass is a measure of how much matter there is in an object, and it doesn't have a direction. You can't really convert kilograms to pounds. A kilogram weighs 2.2 pounds on the Earth, but weighs about 0.4 pounds on the Moon. In interplanetary space, a kilogram has a weight of zero pounds. The book is being really pedantic about this.