Export to CSV, import to Google Shopping

You can't export the CSV via the products listing and import it in Google shopping.
Google does not recognize that format.

For google shopping, you need to go in the options of the google products plugin via the joomla plugin manager and click on the download link there. It's explained in the documentation:
www.hikashop.com/en/support/documentatio...google-products.html

Going on www.therollerskate.com/index.php?option=com_hikashop&ctrl=cron
I can see that your cron was triggered.
So it seems to be working.
You can check that in more details by following the documentation there:
www.hikashop.com/en/support/documentatio...cron-task.html#check

Google Merchant does not require a URL for the xml file. The xml file is uploaded automatically by your server to google's via FTP. So I'm not sure of what you're talking about.

You indeed need to create a FTP account in Google Merchant. Then, you can enter the credentials of that account in the options of the plugin so that it can connect to the FTP server of Google to upload the xml file automatically.

I'm not sure why you're talking about folders. I don't remember about a folder setting for that.

Are you sure that you cron is working ?
Did you set the cron system to send you an email each time it is triggered and did you receive the emails ?
Could you do a screenshot of the plugin's options (you can grey out the password/username)

What if you update your google products on your merchant account using the xml that you can download via the trigger link on that screen ? Does it displays any errors ?
Do you have any errors or messages regarding that photos.xml file on your google merchant account ?

The mpn attribute is only added when the "add product code" option is turned on in the plugin so you should do that.
the brand attribute is only added when you have something in the "brand" input field of the plugin's options. I see that you had it filled in your screenshot. Did you empty it since then ?

The "google product category" option is not implemented at all in the plugin. That's because like for the other two parameters they are optional. It's strange that you get these errors.
For that last warning, the only way to remove it will be to add a line like this:
$xml.="\t".'<g:google_product_category>CATEGORY</g:google_product_category>'."\n";
where CATEGORY is the name of your category based on the explanations there (you need to choose between the list of possible categories on that page):
www.google.com/support/merchants/bin/ans...?answer=160081&hl=en

You can place that line of code just before the line:
$xml.="\t".'<g:shipping_weight>'.$product->product_weight.' '.$product->product_weight_unit.'</g:shipping_weight>'."\n";
in the file plugins/hikashop/google_product.php

Then, try to download again the xml and import it in google again. These error messages should not display anymore.

Yes, you need to use FTP for that.