I agree with the darning foot.. That foot is wonderful ! But check out the Big Foot too for Free Motion Quilting ( FMQ ).
As far as stitch in ditch.. your needle is most likely breaking do to tension... loosen the tension. That is a must and you can keep your feed dogs up..
I have had little success with the walking foot.. that is an added foot that the top and the bottom fabrics are moved along similair pace..
Good luck ! Utube is your friend.. Google around and ask for machine tension and free motion quilting too.
Ell