I have the more common semi-posterior incision, so I can't help you much there. I think sitting is better than just lying around, though! My surgery was 6 weeks ago, so I can sympathize. I found that a recliner was just the thing... you can sit when you want, and if you get uncomfortable, you can lie down.
I think keeping pain under control is the most important thing to do, and you're just coming off the heavy-duty stuff from the hospital. I think it's normal for the first several days home to be figuring out for yourself what works with the pain killers they give you. I took a pill and water with me to bed, and if I woke up at 2 am, the pill was there and I didn't have to get up to take one. By the end of the second week home, I was off all pain killers.
For icing, I was doing it pretty much all day, every day, for the first week I was home. I got two of those bigger ice gel packs from the hospital, they seem to last three hours or so. I have a big ice wrap thing for a shoulder that holds one of those ice packs pretty well, and it has long straps so you can keep the bag on all the time, and even provide a decent amount of compression. It also keeps the bag in place while I was sleeping.
It does get better! At six-weeks post, I'm walking a lot, sleeping normally, driving normally, I can ride a bike for 15 miles or so, and the last walking stick was put away a couple of days ago.
Best,
Jim