Regarding the fat and carbs combination - you can pretty much ignore fruits and veggies - he's mostly talking about grains. This only works to a point though, if you have 2 cups of carrots, that's a lot of carbs and will have an insulin respnse. I'm pretty strict so I only have my fruits with my P+C meals.
One tip - it's recommended to have a P+F meal before lifting as this will increase the fat burned and create a greater insulin response to Surge - thus increasing protein synthesis while also increasing fat burning. However, some people have shitty workouts without carbs before, so try it out.
You're correct in that 9 cals are in each gram of fat - and starting at 30% is probably a safe place - however be aware much of this is individual based on insulin sensitivity and such - I happen to have some insensitivity so I do much better with a higher percentage of fat - like 40-50%. Also, if you're trying to drop fat mass and thus want to keep carbs low - add more protein - Dr Berardi recommends lots of protein - even 2g/lb isn't that much so don't feel like it is. Also, depending on your body you'll probably want between 100-200g of carbs - you'll need to experiment a bit.
As far as how to adjust your calories - the basic deal is it depends on your lifting program. It's the training that decides what calories come on or off as muscle or fat - so just keep adjusting until you reach the limit that you want. I.e. if gaining 1 lb of fat for every 4 lbs of muscle is fine with you go for that - it all depends on your goals. But if you're gaining muscle and no fat - you'll probably want to increase cals. If you can be patient and disciplined - go slow and steady and you'll get to the right place and learn a lot about how your body responds to eating and training.
Don't forget the value of a food and training log - it will make future goals that much easier.
You're on the right track keep going.
BTW - I combine cottage cheese and peanut butter in a food processor and put that over celery - it's quite good - you just have to work out the consistency.
As far as adding more fat to tuna salad - omega-3's in the form of fish oil is perfect. Also flaxseed oil or Udo's Choice are good - most people take them straight from a tablespoon. Also - cheese may or may not work. I do well with cheese but not everyone - try it out.
And I can't finish without mentioning spinach. If you want to follow massive eating and Dr. Berardi to the T, you can't forego this veggie. It's jam-packed with everything you need with such few cals it doesn't interfere with anything. Throw some olive oil and vinegar and some other veggies and make a salad.
Keep working at it.