@JRBear Glad you are having fun with the game! So many things to discover. ;) Let me try to answer some of your questions.
1) The only way to stop children from aging is to turn off aging for everyone. Control +shift+ C opens the cheat box. Just type in aging off and hit enter. If you want to have them age again open the cheat box and type aging on.
To force age a sim, open cheat box and type boolprop testingcheatsenabled true and then press enter. Shift-click on your sim and click 'set to birthday'. They will then age transition. Type boolprop testingcheatsenabled false in the cheat box to switch the cheat off.
2) Werewolves come out at night. Look for something you might have thought was a dog, only it has glowing yellow eyes. They tend to visit your home lot. When one visits, go out and great it. Make friends with it and it will nibble your sim turning them into a werewolf.
3) You can not visit other households without a mod. Only community lots.
If you have any more questions don't be afraid to ask!