Check your PM's
3 Gallons is perfect for now. But make sure you upgrade to a ten gallon as he grows.
And make sure you keep his tank clean!!! These frogs are also notorious for Red Leg and other Bacteria infections brought on by the massive amounts of waste they produce.
You might want to treat your frog for chytrid. Even if it might not have it, its a good practice for acclimating new amphibians.
Here is a link explaining Chytrid and the treatment.
Chytrid...the fungus among us - talk to the frog
After the treatment a lot of frog owners have reported better and increased eating habits!
As crickets go, I would get a small cricket keeper which is available at any petco/petsmart.
The keepers have nifty little tubes so you can just knock the crickets into the enclosure.
And Make sure the Crickets are well fed/Gut loaded, The healthier the cricket the better it is for your frog.
I recommend a varied diet for any frog, But Many have been very successful at keeping their frogs on just Night Crawlers alone.
I don't think the schedule that the pet store had really effects this species of frog. They always seems ready to eat. LOL
More over I think a Pacman Frog makes an excellent Dorm Room Mascot.
I hope this helps!