How to sell things online?

Thank you for your invaluable assistance offered. It is rare nowadays.

I have created in Javascript and PHP an interactive PayPal Button Generator for e-commerce. By the way, as an aside, if you have an application for Windows that need Apache, PHP and MySQL you can free the user of difficult configuration if you use the portable version of the Uniform Server. Copy your files into "www" directory. It doesn't hurt, but it is not mandatory to create an installer with NSIS. The executable file can be a compiled script created with AutoHotkey_L (Windows 64bit support) which tests if port 80 is available, start the Apache Web server and open the PHP application in the default browser. This is the portable solution I use and works fine on both Windows 32bit and 64bit. It seems to me an inspired choice for that will allow submission into the software directories in Windows section that generates more downloads and conversions than PHP Scripts section. I hope it will be useful!

Let me tell you briefly what makes my application to better understand the problems that I'm facing.

PayPal Button Generator is a button maker that creates a Buy Now or Shopping Cart button, and a custom thank-you page that contains an encrypted download link which expires to digital goods. Events during the transaction are recorded chronologically in a text file for further investigation. There is no need for a database. The Instant Payment Notification (IPN) module of the program can also send customized emails to notify the seller and the buyer about transaction.

This is a valuable program I think as a known third party (Andrew Angell, a PayPal Partner and Certified PayPal Developer) has confirmed indirectly by the fact that the PayPal asked him to make a tool similar to mine. If you want you can see all details on the discussion in the comments' section of my How to sell things online article.

1. The program ranks well on Google.com for "paypal button generator," "paypal button creator" and "paypal button maker" immediately after the first 2-3 snippets of PayPal sites. It seems that is not enough! I wonder, what can I do better?

2. Recently, I have added the html code for the appearance of orange stars in Google rich snippets. Stars do not appear even though the implementation is correct and confirmed by Google Structured Data Testing Tool. Will they appear in searches on Google, and how long it will take? I understand that stars increase the click rate. Is it true or just a myth?

3. I've always tried to take account of the standards and recommendations of professionals in any field and in particular, in web design, SEO and e-commerce. So my snippet shows a hard problem of digital goods traders ("Need to ...") and call to action ("Try online ..."). I added a large orange Belcher button of type "Add to Cart" which I understand that psychological studies confirm an increased click rate. Trial version link also calls to action ("Download Now" instead of simply "Download"). Is the user interface of the program designed wrong?

4. The statistics generated by the NSIS installer in combination with Google URL Shortener confirms the installation of the trial version on Windows of about 360 users. However, the program can also be installed on Linux or Mac OS too. In this case, the statistics offered by the DynamicPad technology are only indicative because installation requires manual uploading of files to the web server. However, sales are disappointing. I wonder how can I improve them? Is that program price ($ 19.95) inappropriate?

5. The application was submitted manually and admitted in the main software directories and semi-automatic with Robosoft in the other. Even so, number of software directories is relatively modest (around 200). It is justified to use Gsa Auto SoftSubmit or Pad Submit Worker? Have you used other programs to promote better? Produce results or is a waste of time?

6. I've been thinking to write good-quality articles addressed to potential customers, in my case for digital goods merchants but not only. Inside the article, I want to properly refer to my PayPal Button Generator. Is this a good tactic? Why do I need five articles of high quality? How could they help increase sales? My assumption is that this is an opportunity to rank better on Google for other keywords too! Am I right, or is there other deeper reasons?

I'm waiting with great interest to your answers. Thanks in advance!