MFP and Multiple Third Party Applications & Devices

Let me start by saying, I am entirely new at this dieting and exercise stuff. A week ago or so, I came across a photo of me four years ago. I was approximately 90-100 lbs. After standing on my scale I saw that I was 145 lbs., which let to this. For the past few days I have been using MFP to help me track my calorie intake. My goal is to be about 110 lbs. I have noticed my scale giving me a weight of 135 lbs. the other day. I assumed there was some kind of human error when I first weighted myself. I have already ordered me a Horizon Adventure 5 treadmill, a Withings Scale and soon I want to get a Bitfit Charge HR (after I meet some goal I have not set for myself yet). If you have an idea what that goal should be please share.

With all this extra applications and devices, I wonder how accurate they will calculate my calories, workouts and activities for the day. My understanding is MFP makes an estimate of how many calories your born a day based on you activity level selected in your profile. While Fitbit gives a constant calculation of your activities throughout the day. For example, assume MFP say I will burn 1000 calories today but Fitbit calculated 1500. This means Fitbit will add 500 calories burned to MPF. At least that’s a rough understand of how it work without getting into time stamps.

My question really comes down to how should I go about using these applications. Should I use MFP for my food, Fitibit for my activities and use scale every morning. How often do they sync and Do I have to manual sync each application and how does that affect the time stamps. Should I also use the Viafit application on my treadmill. Will it help to keep a better accurate account of my workouts or should I just completely ignore the Vitfit application. Again I am new too all of this. I have absolutely no idea what I am doing.