1. When drive combos enabled for explorer panel and MC window size is quite small, buttons (tree, root etc) are not visible.
I see 3 ways to resolve this.
a) Additional button (like arrow button in old MS Office toolbars) may appear which shows something like popup menu with inaccessible buttons
b) Bar wrap, i.e. buttons which don't fit bar width should be shown at next line
c) Additional toolbar (like drive bar)
2. Current file info. This was already suggested but it is especially actual now because of list mode.
In list view mode you can't see current file info (size, date, attr ...), so maybe a section in status bar can be used for that?