Your profile always display your Username, Following and Followers, Likes, Check-Ins, Gallery, joined Groups and your average steps. You are not required to show any other information unless you want to.
Once you joined a group, your profile page will be show on the group member list.
Anyone can see the information you choose to display on your profile, whether they join the group or not, unless the group you joined is set as private, then only your group member could view your profile page.
You can view and edit your profile by going to "Me" tab and tap on the username or Icon.The "Edit" button is right next to your username.You can edit your username, Icon, location, your personal website and bio(all optional).
The 'Edit Profile' page is also where you connect with Email or social account. (This wouldn't display on your profile.)