Hi and Welcome to Connect, I also had open heart surgery for my heart transplant so I can share my story of recovery.
It was performed on Jan 5th 2018 and I spent the first 2 weeks in the Hospital. Then to be closer to the very heavy schedule after the initial stay of checkups on a daily bases along with testing which are mostly about rejection so much more intense than I hope you will have. So the Mayo Hospital in Arizona is 80 miles from my home and the daily driving by my wife would have been tiresome. So we spent the first 2 weeks in a hotel near the Hospital. Then just about 1 month after transplant we went home and planned trips as needed to the Hospital for checkups.
I was not allowed to drive for the first 6 weeks due to muscle repair and medications. Also as @bjanderson said the hardest part was getting in and out of bed. I also had a Heart shaped pillow I still have as a memory all the great nurses signed so i use it to remember the great care I received. I would press it against my chest anytime I would cough, get up or lying down. I'm not sure if they will need to spread your ribs but lots of healing going on and the pain mostly is tolerated better with pressure on your chest. I also had a chest strap device they were testing that I found useful also to press against my chest with 2 handles. It was handy as I wore it and the times my pillow seemed to grow legs and hit the floor I knew exactly where this was. But I still used the pillow for times when I got home.

So my concern for you is those stairs. I had the hardest time recovering enough to climb up to the second floor of our house so for the first few months we set up a bedroom downstairs for me to not have to climb the stairs. Now my situation was a bit different in as much that I spent about 2 months in the hospital before the transplant and with my constant heart arrhythmias I was in bed alot. My muscles were in really bad shape by the time I got home. So depending on your strength you may not have a problem. What does your doctors think about those stairs? I had to strengthen my legs and did daily exercises so as they got stronger I started a few steps at a time and over a couple of weeks period did finally make it upstairs. I'm thinking back to those days now as I write and now over 4 years later seem like another life. I can now hike and walk and I do over 5 miles and regularly walk every day at least 3-4 play golf and work on projects around my house. So I hope that helps a bit and let's me know if there are any questions you can think of. Here is my pillow and I also might suggest jotting down your journey in a notebook as I sometimes wish I had done more of that.
Blessings