Proactive is great planning. Just don't burden yourself with 'over active' planning. Post op is a learning curve for us all. I advised my neighbor friend to get one bag of men's diapers and one of large-ish pads. Then next purchase adjust to what may work as well or better.
For the catheter, I just a simple strap or even string in one of the bag's top holes used for hanging on a hospital stand. The other end I'll attach something I can trap under my pants belt. That way the bag hangs free and doesn't follow my leg when I walk. That way I avoid the bag pulling on the hose with every step I take.