I think many of the questions you have would be cleared up by taking a look at the integration guide for payments standard, here is a link:
PP_WebsitePaymentsStandard_IntegrationGuide.pdf
Here is what is listed for these first two inputs you have:
no_shipping Optional Do not prompt payers for shipping address. Allowable values:
0 – prompt for an address, but do not require one
1 – do not prompt for an address
2 – prompt for an address, and require one
The default is 0.
no_note Optional Do not prompt payers to include a note with their payments.
Allowable values:
0 – provide a text box and prompt for the note
1 – hide the text box and the prompt
The default is 0.
To make it so the user can set their own quantity values you will need to find the quantity input in the form and change it to be a text type of input instead of hidden.
There are no options that I know of for adding more than one item at a time to your PayPal shopping cart. The only way that I could see this being done would be to use eCart as the shopping cart on your site, then submit the entire cart to PayPal when it is time to transact.
You could then create a page that would allow you to trigger two add to cart server behaviors with the press of a single button.
