This forum is the best for asking rules questions about the information in the Beginner Box.
The main Pathfinder Rules forum is for asking questions about rules in the Core Rulebook and in other additional rules that are published in various supplements.
Because there are a few differences, you're likely to get inaccurate information if you ask questions about how Beginner Box rules work by posting in the main rules forum.
There are several other other published adventures written using the Beginner Box rules and you can easily convert most adventures written for Level 1-5 characters. It's mostly a matter of removing things from the monsters/opponents stat blocks and making sure that any of the problems the characters are supposed to solve don't require skills or items that are not available in the Beginner Box.
If you haven't grabbed the supplemental material, be sure you look at the Hidden Mine Adventure in the Game Master Kit, and then all the Beginner Bash Demos, which are short adventures for introducing new players to Pathfinder
They have maps, and more plot hooks that you can use to create and run your own adventures.
If your group really loves this, I'd suggest introducing them to the full game as soon as they are willing.
As you get started, everyone can use Paizo's online rules as reference until everyone is able to acquire a copy of the Core Rulebook.
I'd suggest sticking with the Core Rulebook until you are comfortable as a GM in adding more complexity.
Free Beginner Box Resources
The Hidden Mine Adventure is in the GM Kit.
Your players will find more information, and another character class (Barbarian) in the Player Pack
More short introductory adventures and maps are included int the Bash Demos.
The Transition document will help you move your BB characters into regular characters and you can also learn about joining the Pathfinder Society, which has many local games, plus an immense amount of online gaming available.