Not sure how much help I'll be but will try.
1. How do I list new items with the new auction template/store and how does that get added into a listing created using auctiva.
Here's a link that may help with using your own template.https://community.auctiva.com/eve/forums/a/tpc/f/6881044121/m/1251067521
Once you get it all set up, follow through with creating a listing and posting it to eBay. I save all my listings first to make it easier for changes. This may be an unnecessary step but it works best for me.
2. As for hosting images, where do you suggest one would do that ?
I think Auctiva is the best for hosting your images, especially since you'll be listing through here.
3. What else do I need to do to start. I did watch one of the tutorials but still a little unclear.
You can also create your profiles and once they're all set up, it makes it so much easier and faster you won't believe the time it saves. Here's another link for doing that.https://community.auctiva.com/eve/forums/a/tpc/f/579609941/m/7301083762
After you've given it a try and should you still have questions, maybe come back and be specific with what you need help on to get started?.
Keep in mind your listings will not appear for a few hours. eBay has to index them and when using a third party listing service, such as Auctiva, they confirm your account hasn't been hijacked or anything before they get posted.