Yes, we cut all the feet out of DD's sleepsuits. I fully intended to hem them, but never got round to it, because, you know, BABY and she looked very scruffy! I still have all the feet I cut off the suits in a little box with scan photos, don't know why though really, weird thing to be sentimental about.
Agree also re: the white leather boots you usually get given first, I could just not get on with them at all, DH had to deal with them. Eventually DD kept escaping from them and I had to insist (I'm sounding like a bolshy cah but am not really, honest) on getting the nice suede one which were amazing, so much easier. SO MUCH easier.
I think they might be the ones that Ponseti designed and we were told that they were really expensive hence the NHS prefer to use the white leather ones which are just as good. But they aren't as good if parents can't use them and make the whole thing seem really daunting iyswim - as soon as DD got the suede ones, with 3 buckles, it was a piece of cake comparatively. The main problem as previous poster has said is parents not sticking to the treatment, so anything that makes it easier is good!
And yes to the bar making nappy changes easier! Plaster cast stage though, those dudes get dirty! Bright orange baby poo stains, boak. They are also heavy, on a small baby! DD was 2 weeks and they weighed as much as she did, and she was uncomfortable, and didn't sleep well at first etc. Not trying to scare you, just prepare you... 
Also, be prepared that if your small baby has plaster casts on, people will give you the side-eye and assume that you have dropped it. I did not like this.
And also, it might be worth considering referring yourself for counselling, not because it's a terrible thing or anything, just to maybe process your feelings about it, esp because as you say, your DD1 also has health problems and it might just help you to have a private space to be allowed to feel dbfsjkdfkjskjf in, in order to come home and be superhero mum again? You will be fine, but be sure to look after yourself too!
Sorry for rambling....