I think @jeffmarc is right that regular sweatpants are fine with the leg bag. I did find the breakaway pants useful since I drank a lot of fluids and tended to fill up the leg bag rather quickly (especially if I took a nap), so I preferred the larger "night bag" for sitting around the house. With the larger bag, the breakaway pants let me easily adjust the tubing since the tubing wasn't confined to the pant leg. Again, for sitting around the house with the larger night bag, I liked keeping it off the floor so I used a cheap plastic bucket from the dollar store. Not required, but I found it handy. Don't overbuy the pads and underwear. You'll need some to get started, but you'll have time to get more once you figure out what you need. Like @jeffmarc, I found the Depends worked pretty good. After the surgery they gave me the leg bag and night bag with elastic straps. I guess some places use tape. The elastic was good since it didn't pull my leg hair but I did need to keep an eye on it as during the day as it'd slowly slide down my leg and start letting the tube pull on the catheter (which is not good). You need to keep an eye on it. Also, my wife insisted we use disposable gloves and alcohol wipes when switching bags, etc to prevent infection. And antibiotic gel to lube the catheter where it enters the penis. I did have a disposable waterproof pad on the bed and one night I must have moved in my sleep and pulled catheter out of the tubing. The tubing fell in the bucket beside the bed but the pad did it's job and kept urine off the mattress. Best wishes.

I wore baggy sweats and strapped the catheter to my ankle just above the cuff on the sweats. I used Depends and then switched to pads at about 30 days post op. Also used bed pads, just in case, for about 90 days.

GOOD LUCK!