I took out my mortgage a year before I started playing the miles game so I cannot speak from experience on that. HOWEVER... I can attest that my score has gone from a mid 700 to a high 700 / low 800 in ten months. That's with at least ten pulls and it still shot up 50 points or more.
For me, taking out lines of credit was a huge boost because it gave me a bigger credit line and thereby lowered my utilization. Every situation differs though, I guess.