As a buyer I am asking why a seller would even mention these things? 

1.  If you haven't received any email from us after 5 working days money has been transferred, please send email (quote      the payment date / time / reference / bank branch number/ bsb number, etc ) to us. We will chase it up for you. 

 OK ,so I have paid (and within the time requested) and it's now day 5 and you haven't communicated with me yet  so I must email you and you will kindly 'chase it up for me'. 

Well that's just such a very generous of you to go out of your way and such a thing for me (you paying customer)

         2.  We suggest our customers to leave feedback after the item(s) received. 

yes that makes sense.If I want to leave feedback I will do so and do so as I feel appropriate and only after receiving the item I have purchased.
         

3.  After we receive your positive feedback, we will do the same for you at the same day. 

So I can't expect feedback unless I leave positive feedback?

 4.   Please keep in mind that leaving negative feedback before contacting us will end all communication between both parties. If there are any problems, please contact us as we will definitely try our best to solve any issues!

I'm thinking if I hadn't heard back from my message sent (as instructed) on day 5 after making  my payment, I may not  bother trying to contact you ? 

and re saying all communication will cease between both parties ?

really ? lol