>For the push and Talk : Is that you can be in contact by message with others that have the app : Like a chat.
You can implement such a capability but it would require significant custom development (javascript). If you are proficient with web development you can search from examples open source web chat systems that might provide a starting point.
>And also if it is possible to send Notifications to the people that use the app !!
Push notifications are not supported yet. The new version of App Center that we are working on will provide later this year.