Customize Sharepoint Website (only using SPD)

I have a sharepoint website with entry forms, lists, pages which is almost finished. I need a sharepoint design expert to help me finish the website in the following 48hrs. It is important to note that the website can only be access using sharepoint designer, and all changes needed should be done this way. Things needed: - After dropdown field is selected, auto populate other text fields in the same entry form page with data from a list. - After dropdown field is selected, show only related information on a 2nd dropdown field in the same entry form page. - Assistance with workflow to update product inventory count after order has been placed. There could be some other extra work like this in other projects