I'm confused about calorie calculating.

I understand the basic principal of adding calories, ie. 8 oz of black coffee 0 cals 1Tbsp cream 29cals 1tsp sugar 16 cals comes to 45 calories for my breakfast coffee.

However I have trouble getting into more complicated meals or dividing portions.

We've purchased a food scale to try making it a little bit easier knowing exactly how much I'm eating.

I was considering doing a whole infrared oil less fried turkey and portioning it out for a few meals for our family.

My confusion in this specific instance pertains to how to calculate the calories.

100 grams of roasted turkey calories are as follows (university of illinois)

Breast with skin 194 Breast w/o skin 161

According to hungry-girl:

3.5 oz deep fried turkey has approximately 190 calories 3.5 oz regular roasted turkey breast typically contains 165 calories 3.5 oz skinless roasted turkey breast 140 calories

I cannot find ANY information on the calorie difference between actually deep frying a turkey and using the oil less infrared method.

Roommate told me that the difference in roasting or frying was just 3 calories and to not even worry about it. Which I don't believe is true.

How can I correctly calculate the calories per portion size based on food preparation method?

It seems that there's not one single reliable source for calorie/nutrition information. How do you know which numbers to use?

When making something like a homemade soup or "all in one" pasta meal, do you just add up the amounts and calories of each ingredient added? Then divide and assign your calories that way?

Say I melt 8oz of shredded cheese into 16oz of cooked pasta. I can visibly see that the cheese is not 100% evenly distributed, but is it just so negligible that you just divide those cheese calories by 8? do you just add the calories together for the entire meal? then divide that number by how many portions you separate it into?

I know that it's probably a minimal difference but over a long period of time wouldn't those fudged numbers hurt/help you?

Like you underestimated 25 calories on every meal, that's 75 calories. What if you did that for a week? 525 calories. 6 weeks? that's 3150 calories...almost a full pound of additional weight gained or lost.

Should I just prepare all of my food separately, even though I'm preparing meals for 5 people?

I'm very VERY new to calorie counting obviously, so maybe these questions sound stupid, but I did read the FAQ before posting and didn't notice anything regarding this. So if this post should be directed to another sub, please let me know.