I think 7 stairs. Enough for me, im kinda pussy with stairsets. I can only whip em atm. I was able to do 360s down any stairset i can whip, but i havn't done em for a while.
Also, the concrete ledge is relatively clean and in pristine condition. With some lacquer, some or wax, or just lots of balls, you might be able to gap to boardslide.