Welding:
Try Model > Effect > Cleanup with the merge vertices option enabled.
Edge Turning:
I don't understand the "so that the normals are better aligned" part., but SI3D Doesn't have any edge manipulation tools. You can select and collapse edges, but not manipulate them. To simulate this, you can tag the 2 vertices defining the edge and follow up with Model > Edit > Centers2Vertices to put the object's center inbetween the points. Then, you can manipulate the edge in TAG mode.
Hope this helps.
Matt
Matt Lind
Animator / Technical Director
Softimage certified instructor:
Softimage|3D
Softimage|XSI
speye_21@hotmail.com