Weighing is the best method we have and is still pretty accurate provided you are weighing individual ingrediants (e.g. raw chicken or uncooked rice). Weighing foods with addatives (e.g., fats) won't be useful.

I haven't seen studies for significant alterations of calories with food preparationoutside of nuts (whole unprocessed vs. roasted and processed).

I agree, the act of measuring and tracking will help limit food, even if your count isn't 100% accurate.