Fitbit and MFP integration: please explain the calorie adjustment in plain English!

Hi all, I've been an on/off again user of MFP for awhile now. I'm trying to get more serious and consistent as I get older.

I recently bought a Fitbit and synced the Fitbit app with MFP. I'm very confused about the Fitbit and MFP relationship when accounting for calories.

When I first synced I read on the Fitbit website to enter my exercises on MFP only, not on Fitbit. I don't fully understand this because the Fitbit workouts are automatically added to the Fitbit app.

Needless to say, I did an Insanity workout and burned 515. I followed the instructions and input this on MFP. Then the Fitbit adjustment came, adding about 250 calories to my allowance along with the 515 allowed by the exercise I added to MFP, adding a total of 764 calories to my allowance.

This didn't seem right to me as someone who is looking to drop some pounds. I checked the Fitbit website, which advised NOT to add exercises to MFP and the Fitbit app would make the calorie adjustment. So I deleted my original MFP exercise leaving the extra allowance at 250.

I know this is a lengthy post, but I'm very confused by this and want to get the most from both apps. So what is the right way to do this, and is it the same for weight training?

One thing I noticed is you can add a weight loss goal to Fitbit, but it doesn't ask you at what rate you want to lose the weight like MFP does. Will this matter when Fitbit makes the adjustment?

Thanks for any help. As you can see I'm pretty confused!