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.
April 30 Goal: 185.8 May 31 Goal: 178
; Independence Day Goal: 173
; Halloween goal: 155
New Year's 2016 goal: 145
May 31st Goal