ECart Help Needed

Hi
I am building a shopping cart and am using PayPal checkout, every thing seems to be working ok after a few adjustments to the scripts generated by the latest ecart checkout wizard.

1/ I have noticed that if I place an second order within half an hour or so from the time of the initial order, the order ID is overwritten with the new details and the first order details are lost, I thought about killing the session but as I need to force the user to register at checkout this does not seem to be an option, any ideas on how to overcome this?

2/ I need to update my orders table with a value of 'Completed' I set an initial value of 'Pending' on the confirmation page, on my IPN page I have added a update record behaviour to change the value, this is not working and its getting pretty confusing, I'm sure I'm nearly there with it, but feel this is something I need to ask if you could take a look at to see what needs to be done.

3/ I would like to update the products table to deduct the quantities of the ordered products from the values stored in the products table, I haven't done anything with this as I feel I must get the status updating correctly first.

4/ I would like to display the details of the order on the checkout_success.php page, and send an email to the user when the page loads confirming the purchase and order details.

Any advice would really be appreciated, I have attached the files and will purchase a support ticket if needed as I have a deadline to meet and its fast approaching.

Thanks in advance