Dynamic suite

Hi,
I’m developing my own site for music downloads to my customers. I have the dynamic suite and have applied all the techniques available via the tutorials. I have signed up with PayPal standard business account. I have 3 questions regarding your software.
Q1:
How do I stop an order register in the database when confirm is pressed before going to the PayPal standard account. If a customer decides to cancel at the PayPal stage, a record of paying is shown in the orders database. I need to stop this. Would the same result happen if I used a gateway like Authrize.net?
Q2:
Is it better to develop work in localhost mode or develop work from the server? Is there a difference in order for the code to work?
Q3:
I followed the tutorials on customer order history and download centre and when I test the site locally I get a no record message, even though there are orders in the database. How do I resolve this?
Thank you for your time. Denis OToole.