well some machines may differ but i have never altered anything. just FMQ with feed dogs down or up. took a class and was told to leave them up. mostly do it with them down though. i don't change stitch length because how slow or fast i move the quilt determines the stitch length.
you must lower your needle and up again to pull the bobbin thread up to the top, hold onto both and start stitching almost in place. a few tiny stitches. then stop needle down, and then clip those threads out of the way.
fairly fast foot pedal speed and slower movement of quilt speed and you should do fine.