post sign up and login credentials to related pages
Is it safe to post the login and/or sign-up credentials from the homepage (index.php) where i plan to embed the forms? (i use HTTPS)
The login.php and the sign-up.php pages will still exist but only for completing the procedure and for secondary try if anything went wrong.
Is there any other suggested solution to make this possible?
Yes, it's secure and essentially the same. The source page (the page you're on) doesn't matter because the browser creates a new request that submits to the form target page only. But definitely using HTTPS is a good idea.
Hope that helps, let me know any other questions.
We just use those variables to keep all the information in one place. So you don't need to hardcode URLs everywhere. Feel free to try doing it a few different ways and adapt it to what works for you.
One way to get started would be to copy and paste the code from the existing user-login or user-signup pages.