To measure the distance you can use either a watch like the Garmin with a GPS that tracks your movement, heart rate, distance, pace etc... (its my fave). Or you can use something like Map My Run MapMyRun.com - Map your Run, Running Routes. Find Runs Anywhere. Join our Running Community of Runners. Run GPS, GPS, Running Social Network. Google Map Run, Calculate Calories, Online Pedometer, Distance, iPhone, and More.
I think all you girls are doing awesome, the other thing I found that really helped me was having a running partner. Someone that you can make plans with to run, who will push you to go out there even the days that you don't want to, and who will challenge your speed and distance. In canada we have running groups and clinics you can join. I used to run with my roommates in university, then Running Room clinic, etc...