Try the code snippet below:
vFaces = myFeature.GetFaces()
Dim i as Integer
For i = 0 to Ubound(vFaces)
Dim swFace as SldWorks.Face2
Set swFace = vFaces(i)
vEdges = swFace.GetEdges()
Artem solution should help you with getting faces and edges.
To select sketch:
If you just draw this sketch you don't need to select it.
If you want to get selected sketch that it's already selected you don't need that to.
If you need to mark it then you need to get selection.
Perhaps problem is related to getSelectedObject.
Try to use GetSelectedObject6 Method (ISelectionMgr)
and remember that you need to specify mark to -1
does not required a mark