AC 43.13, welding and a hip-check

Background: I have a wing strut with a bend in it and it may also be
cracked.
Looking thru AC43.13 at various welding options raises some questions:

Paragraphs 4-92 (Repair by Welded Sleeve) and 4-97(Splicing using
Larger Diameter Replacement Tubes)appear to apply. When would one
technique be used over the other? (NOTE: I am not going to attempt
this repair, just getting familiar with the terms)

In another example: Inspecting another strut, the A&P points out a
slight bend and opines it was caused by someone pushing on the strut.
What are the circumstances that would allow me to straighten a member
( i.e. using a little hip action) vice having to resort to welding? -
Mike