Party Tuesday or NO party? Gah!
There are a lot of steps in my house. The second floor is actually open floor plan, so the entire upstairs, you can see down to the first floor from anywhere up there, meaning that one could fall down the stairs or from anywhere upstairs into to the first level of the house (hard wood floors), BUT by the time my child was 6, he knew how to not fall off the second level and how to go up and down the stairs safely, so I don't know how much supervision a 6 year old really needs in a house he's familiar with, stairs or not.
The only thing i have to remind my kids (and myself) of is NO SOCKS on the wood stairs! You WILL slip and bust your a$@ and I think we all have at some point.
About the rumored planking...he seems a little young, but if he watches MTV or has friends with older siblings, he definitely could know about planking.