These 'issues' are all limitations to the gateways you are using.
For the vendor to receive order updates, you need to configure your account with the gateway to send notification emails. both the paypal and eWay account need to be set up to send order notifications to the account holder.
For the eWay orders to send emails, you need to configure the eWay account to send those emails to the person placing the order.
eWay is a remote checkout method. this means that the checkout process is not in real time. in other words, when the purchaser goes to the eWay site, they enter payment info, and are then directed back to your site.
At this point, the transaction is in a queue to be processed on a first come first served basis, it has not actually been processed through the bank yet, so there is no way to know the success or failure status of the order.
This is why the return page does not send an email or store the order information, because the status is not known yet.
Paypal Express is a real time gateway, so it will store the details and send the order info.
if you want to have the emails sent and order details saved, you should use only Express Checkout rather than offering both eWay and Express.