As per your scale question, I would look at reviews on amazon, but I will say that you can make sure your scale stays accurate by keeping it only in one place and not moving it as well as making sure it's calibrated.
For an activity (as well as calorie) tracker, I use my fitness pal. It works for me and I like that I can see my activity and food in one place.
Valentine's Day Goal: 190; Easter Goal: 185; Mother's Day Goal: 180; Independence Day Goal: 170; September 26th Goal: 158 Halloween goal: 153
New Year's 2016 goal: 145
Valentine's Day Challenge