Dynamics 365 - CRUD Operation using Web API for Mobile App

Question

Hi,

 

I want to access CRM data using Web API and perform CRUD operation on that. This Web API will be used in external Mobile App which is supposed to have only Data access of Dynamics CRM 365.

 

I have tried with sample code provided in Dynamics 365 SDK.

But, I wanted to know if -

1. I can do the same thing any other than this which allows me to perform CRUD operation on multiple tables at the same time? Example please.
2. If I perform CRUD operation on CRM data using Web API can I use transaction with that? Example please.
3. What are the other possible ways to perform CRUD operation on CRM data? Example please.