1. Is there any feature comparison table to see between the starter and the paying alternatives?
There was a table, but the table is outdated. We are planing a relaunch of the website. Then we have it again 
For your Question: The starter version only support Amazon, Productboxes and Lists. No price comparision, other APIs or WooCommerce (and many more).
2. Is there any XML-feed import? See only mentioned CSV, but who is using that anymore ....
Not yet. XML is a feature request. CSV is used by many people
3. Is there any video showing how to match products from different feeds manually?
No, because these videos are also outdated.
4. Can one product be inserted in any post?
Yes. Just via shortcodes. You can also enable the productpages and dynamic lists.
5. Is there any way to limit, search and choose which products/categories to import from a feed? Sometimes only few are need and not full feed?
There is no automatic import of the whole feed. The plugin just preparing the data. After that you ware selecting the products. Or you can also import products via filter.
Best Regards,
Christof
