A few Delta airlines questions for you all.

We are travelling from Edinburgh to Orlando via JFK next Fri [clap], I have been trying to find the info on the Delta website to see what meals will be offered and in flight entertainment but I cannot find much and do not want to call them and ask these questions! From what I can see we will only be offered a snack and something from the snack basket (eg. Bag peanuts etc) can anyone tell me what we should expect? Can we take food on the plane and does that food have to be bought after security in Edinburgh and anything left will be taken off us when we get to JFK?
Its going to be a long day and we don’t want to be starving by the end of it. Will take food if needed but unsure of the rules on carrying food in hand luggage.
Also according to the website we are travelling on a 757-200 on the way there changing to a MD88 McDonnell Douglas(?) and on the way to Orlando from JFK, will we need to take headphones, do they have seat back tvs or is it the old tv every three/four rows?
Sorry of trivial but is bugging me!