[SalesForce] How to create new apex class and trigger in salesforce professional edition

Professional Edition does not include Apex. You can get a free Developer Org (or more than one) at the Salesforce Developer Site where you have full access to Apex, VisualForce and most other features like Workflow, Process Builder and case management.

Alternatively sign up for Enterprise or Performance edition on a 30 day trial as that will include Apex and Visualforce.

To deploy Apex code into Professional Edition you would need to use packages or AppExchange Apps rather than create in a Developer Org and deploy.

Deploying Apex via Change Sets is not intrinsically different than deploying other components apart from the need to have Test Classes with Code Coverage above 75%

Depending on just how many records you intend to do at once you can use the Data Import Wizard with practically any edition of Salesforce; limited to 50,000 records per run. It is compatible with Safari 5 or later.