you can't do this directly ingame with grid, but what you can do, is editing the layout-file of grid with a text editor.

To do so go to the Addon folder of Grid and open the GridLayoutLayout.lua .

There for the normal profiles (like 'By Group 5') you can specify by setting the parameter 'SortMethod' to "NAME" , that grid don't sort by index, but alphabetical.

Or you could simply add a new profile at the end of the file, if you don't want to change an exsisting, with for example:
Code:
GridLayout:AddLayout(L["By Group 5 Alphabetical"], {
			 	[1] = {
					 showParty = true,
					 showRaid = false,
					 sortMethod = "NAME",
			 	},
		 	})
as regarding for mouse-over-healing, this is realy useful, and in my setup I use it nearly for all my party heals (with hkn not innerspace, but IS should be as good for this as HKN).