Welcome to DC.
If your gas oven is taking longer to ccok familiar recipes, it may be a problem with the oven's temperature accuracy. Buy an oven thermometer and check the temperature readings vs. the setting on the dial.
Cooking in a gas oven should be no different from cooking in an electric oven for most things.
"If you want to make an apple pie from scratch, you must first create the universe." -Carl Sagan