Tarlton,
Maybe having using this system for quite a long time I can help you.
1.
Getting the right sheath (condom cath)It is really important to get the right fit for these. Companies like Coloplast are happy to send out sample packs which consist of several different sizes, a leg bag and a measuring tool to get you started. I used Manfred Sauer for quite a long time and they are excellent with quite a long patch of adhesive. I can only find a
dealership in Canada not the USA but you can request samples from them.
2. The leg bagTo work, there has to be a clear run for the urine to flow because, as you know, backed up urine will blow the sheath off. So it is important when the sheath and leg bag have been fitted to check that the sheath output tube is not twisted, even a little bit, and that the leg bag valve is flat against the leg. I never got on with bags attached to the thigh as I could never get them to flow right (though I am permanently seated of course. I always used bags attached to the calf which makes the job of draining slightly easier as there is some help from gravity. Anyway, getting the valve on the leg bag flat is vital because a twisted valve can easily block with the expected wet outcome.
3. The Night Bag.I found that the 2 litre night bags worked absolutely fine for me as long as they ae used with a bag stand that holds the valve in the proper place. Of course, for 'normal' people there is the problem of tossing and turning in the night trapping the tube. I have to use my hand to move my legs so I never had that problem but I think it is just a matter of waking enough so as to check the tubes.
Let me know is that helps or ask any other questions that occur to you.