We use no more than three eggs to make an omelette = We do not use four/five/six etc eggs
I like that book no more than I like this one = Objectively I like both these books the same amount.
longer = time/duration of time
It will take no longer than 12 hours to fly to America
The school is no longer open.
longer = length
The rope is no longer than 20 feet.
The road to the hills is no longer than 5 miles.
Hope this helps a bit.