Yes, we also had to wake during the day. I had the express as he couldn't latch on and it used ot take him an hour to drink 2oz of milk and that was with constantly doing things to keep him awake like changing nappy, opening windows, undressing etc. He didn't have jaundice though, so it didn't matter so much about the night feeding.
My DS was in hospital (The Freeman in Newcastle) for 6 days when he had the surgery. He was only in Intensive Care for 5 days and it would have been 4, but they had no room for him back on the ward. I was told babies with Downs can be a bit lazy about coming of the ventilator and be on it for upt o ten days, but he was off it quickly, despite having had a collapsed lung. We were very lucky that he didn't get a chest infection, they told me it was almost inevitable. He sailed through it! He had morphine on a drip the first day after his op, then just calpol! Crazy! He was 6lb 14 1/2 oz at birth )37 weeks) and only 11lb at his srugery at 6 months! He did gain much more weight after the surgery, although he's always been a skinny minnie and tiny!
We are very lucky. My DS is very learning delayed and still doesn't have a huge amount of speech, but he is generally very healthy. He has bi-lateral mystagmus, where his eyes flicker from left to right, but it doesn't affect his sight and seems to be improving with age. He has still never had a chest infection and doesn't really get ill at all. He does have a disgusting runny nose almost all winter though! 
I felt much more maternal after I had DS3. I don't know why, maybe as he needed me more? We had no idea he might have Downs until he was born and they didn't notice for 24 hours!
I thought he looked a bit 'odd' and he was tiny, but it was only as I was chatting to a midwife and mentioned how big my other babies were that she had a closer look at him. After the initial shock I was just so in love with him I really didn't care. I still don't now, Downs is a part of who he is.
I hope this helps and you're finding things OK. I do think you have to look for the positives and knowing exactly when your baby will need feeding is one of those!
Sorry, I;ve gone on a bit... 