Is it possible to place a WordPress widget into the main page layout?

of course you can, you can place widgets wherever you want in your page:

1. Define them in a callback function in your functions.php file which calls the register_sidebar() function, and then hook that callback to the ‘widgets_init’ action hook, also in your functions.php file.

2. On the page where you wanna use it, wherever you wanna use it, print the widget with this code, by using the value you specified as the ‘id’ parameter when calling register_sidebar() in your callback:

<?php if ( dynamic_sidebar( 'id_of_ur_widget' ) ) : else : endif; ?>

Don’t get distracted by the name of the function, register_sidebar doesn’t mean that your widget is a sidebar, it’s just the not-so-smartly chosen name of the wp function you use to create a custom widget.