I'd like to pant some flowering dogwood saplings along a walking path near Flint, Michigan. Part of the path is covered in wood chips and part of it is concrete. Two questions: 1) What is the closest distance to the wood chip path I can plant without having to worry about walking into branches, and 2) How far away from the concrete do I need to plant to avoid any alkaline leeching that might negatively affect the trees?

I have 40 year old dogwoods along my driveway (I'm losing some!) They are pretty close, maybe 2', and any low hanging branches can be trimmed. I only have one branch touching the top of my van.
You don't say if the concrete is new or old, but regardless, sidewalks aren't very thick, so I wouldn't worry about leaching. But dogwoods like to be slightly acidic, so I suppose stay closer to the wood chips.
Plan it mainly based on aesthetics.
Have people stand where the trees will go and stand back and squint.