How to set up Paypal on WooCommerce?

I've already tried hard to set up Paypal on WooCommerce without success.

I wonder what is the actual steps used to set up PayPal on WooCommerce?

My problems are:

1. I tested it with my sandbox but, after payment, it doesn't redirect back from PayPal to my website. (I've already had business Paypal account and the redirect url on Paypal is already set)

2. The order status after check out is still 'pending'(unpaid).It doesn't automatically change the status after check out.I've no idea how to make it work?

3. What the difference between 'PayPal Email' and 'Receiver Email' in payment gateway setting?

4. Do I have to do anything to make IPN work?

5. No notification email sent to shop owner...

NOTE: On my status page -> wp_remote_post() was successful - PayPal IPN is working.

Thanks in advance for any helps!

http://wordpress.org/extend/plugins/woocommerce/