I'd also vote to incorporate the store into the new left panel, and allow buying and equipping in one step. Modify the buttons up top where "Unequipped, Equipped and Archive" currently are to include labels:
Parts: [Unequipped] [Equipped] [Archive]
Store: [Purchase] [Sell] [Buyback]
Also, using the mousewheel to scroll when the left panel has too many items should be implemented -- perhaps instead of the previous suggestion of using it to switch exos (unless it could be smart enough to always switch exos, even when hovering over the left panel, UNLESS there was a scrollbar present, in which case it would scroll as long as you were hovered over the left panel).