How to work with api?

Question

API

Hello, I am writing a project on pure node.

There is a task to write a payment handler. On this occasion I would like to ask a few questions.

1. You need to check the ip from which the request came. Those. there is an array with trusted ips, but how can I find out the ip from which the handler is being called?

Will it fit request.connection.remoteAddress?

2. Post parameters also come. If in php I would receive them via $_POST, then how can I do it in pure node js? I think this design will not be relevant?

let body = '';
    req.on('data', data=>{
       body += data.toString();
    });

3. After processing the payment, you need to answer OK. Would it be ok to just do res.end('OK')?

Thank you all in advance!