It won't work because of security.
Search up turn on less secure apps for <application>
for <application> it can either be gmail or hotmail depending on your emial.

Yes you can (in Node.js at least); PHP doesn't work.

yes, if you use an email server, just look up "how to send email using <insert lang here>"

yes, you can!
do the following code in node.js:

const gmail = require("gmail-send");

function sendEmail(){
  const send = gmail({
    user: "YOUR USERNAME",
    pass: "YOUR PASSWORD",
    to:   "RECEIVERS'S USERNAME",
    subject: "SUBJECT"
  });
  send({html: "TEXT"}, (error, result, fullResult) => {
    if (error) console.error(error);
    console.log(result);
  });
}

i dont think replit allows email sending :(