RE: weights on waist: smart or foolish?
I'm not Cathe or trained in any way to say this, but for myself I wouldn't do it. Especially for squats and lunges, in fact. In those moves you want to be very careful with your posture to protect your knees and your lower back, and I think the artificial added weight around the midsection would make it more difficult for you to maintain the right form. The advantage of having a barbell or dumbbells resting on your shoulders seems to me to be that the weight is evenly distributed and doesn't affect your ability to align your lower back and pelvis properly, pull in your abs, stand upright with proper knee alignment on lunges, etc.
Just two cents worth.
TarHeelMom (formerly known around the Cathe Nation as Kathy S.) (see my very own "Handsome 'Heels" sons in my avatar! )