Hi Anne,
A lot of your questions are answered in David's books, especially Sweet Poison Quit Plan, and on this web site http://sweetpoison.com.au/
You need 10 grams of fructose a day and can get that from 2 x 100g pieces of fruit. Or you can use the tables in SPQP to calculate your daily fructose intake. But as a general guide, if you avoid buying any food with more than 2% "sugars" [ about 1% fructose] you won't go far wrong. Yoghurt is OK to 5% "sugars" as that much is milk-sguar andis metabolised as glucose.
There are no "banned" foods - just advice to avoid those containing a lot of fructose.
The important criteria rea (1) you feel full after every meal . . . . can't eat another mouthful, and (2) your weight is under control.
Regards
JohnN