Finder with mini, "spatial" interface but non-spatial behavior

[Egosphere]

Hi. Does anyone know of a way to use Finder with the mini interface (the "spatial" one, activated with the elongated button at the top right) but without the behavior of the spatial Finder where folders open in a new window? I am aware that alt+(open folder) closes the current window behind while opening the next. Ideally, I would want it to actually be the same window, but otherwise I would definitely be interested in knowing how to simply make that the default folder-open behavior, if possible. And, failing that, maybe someone knows a way to hide the sidebar in the "browser" interface (like you could in 10.4)? Thanks for the help!