Caresheet: http://ball-pythons.net/forums/showt...s%29-Caresheet
I started my first ball (also from Petco) in a 20 gallon long and after her not eating I switched to a tub set up and the difference was night and day. I believe the tank wasn't staying warm enough for her and that it was too open making her not eat. A tank can work, it's just not my personal preference. You can black out three sides to make the snake more comfortable, put a wet wash cloth/plexi/foil on the lid to help hold in humidity, and add a heat lamp if you need help keeping the tank warm. Make sure to have the lamp on a dimmer and have the UTH (if you have one) on a thermostat.
Mouse fuzzies are way too small for even hatchling BPs, so unless she was talking about rat fuzzies I would take her advice with a grain of salt (just my .02). You can start your guy on something larger and should see better growth with something bigger than a mouse fuzzy. All but two of my BPs take f/t and it's my preferred feeding method, so it really depends on the snake and if it will take to f/t or not. Some snakes just won't eat thawed and need to be on live.
If your guy doesn't take the f/t I would wait at least 7 days and offer again (a larger feeder than a mouse fuzzy). If it won't take then I would try live. I wouldn't offer more frequently than 7 days as offering too often could stress the snake out.