Re: HOW TO ADD NEW SIM TO THE TOWN?
Easiest is to build a new house and add a new sim
If you have an unoccupied house you can choose the option to Add a new sim
Depending on where you are in the quests, you could add a sim baby by tapping a crib, if the house have less than 4 occupants (it might be 5 or 6 depending on VIP level)
You have (or will get) the option to adopt from a phone using an adult sim, again, depending on your quest progress
As for Community, do a search on FaceBook for SimsFreeplay and choose a group to join.
There are plenty. There are global, local, ones with focus on building design, others with story focus and so on.
Choose one that fits your interests
EDIT to add pic