1)The Starter Plan that you currently see advertised on the Auctiva website actually includes the same functionality as the $2.95 per month Basic Plan you are already subscribed to, so there is no reason to upgrade unless you would like to pay $1.00 more per month for the same package. We recently renamed that package and increased the price but, as an existing subscriber, you are welcome to remain on the $2.95 per month Basic Plan for the time being.
The “eBay Listings/mo” in the plan description means that you can post up to 15 listings per month through Auctiva for the regular Basic or Starter Plan rate. If you were to post more than 15 listings in a month while on the Basic or Starter Plan, you would be charged an additional 50 cents for each listing after the 15th by Auctiva on top of the regular subscription fee.
You are still responsible for paying the applicable insertion fees to eBay for any items that you post through Auctiva.
2) When eBay runs listing specials such as the one you described, listings that are posted almost always qualify for the special rate being offered along with the promotion. I have seen at least one in the past that specifically said listings posted through 3rd party services do not qualify before, so it is generally a good idea to check the promotion details to make sure such an exclusion does not apply.
3) Yes, you will be able to post your auction format listings starting at 99p or less per month through Auctiva and eBay will not charge you insertion fees for those listings in accordance with their current offering you described.
4) Yes, when you are creating listings for the eBay.com (US), eBay UK, and eBay CA sites, you will be able to choose the "International Site Visibility" option in the Marketing Tools section to make it so those listings show up in the default search results on other localized eBay sites... and it should work!
I hope this helps. If you need any further assistance with your account, please feel free to contact our customer support team by mousing over the "Help" tab within your account and selecting the "File Support Case" option.