I would be glad to answer your queries:
1. You can list products of each seller differently. Showing Seller name is possible with little code, We'll happily do that for you if you are on Premium Plan.
2. You are correct, You can change currency to Euros and disable all other currencies.
3. This is partially possible, Either You can ship all products via shop or they can ship via themselves. We can modify this for you as well for some price.
4. Yes, Charging via category is possible in Sellacious.
5. The full amount reaches to your account and Seller just gets the notification. You later transfer the amount to sellers(after charging your fees).
6. We are using many payment plugins. Paypal Adaptive is still in beta. We're doing some experiments with it and would switch to it later.
7. In User Profiles(Sellacious Backend)
8. Order Cancellations can be done by Seller/Admins. The buyer would need to contact the concerned person for this.
9. This would be done in two steps: First, buyer would need to request admin/shop owner for cancellation. If the request has been accepted, Shop would can either refund the money in e-wallet(instant) or can go to Paypal orders and submit reversal.
10. Sellacious has dedicated taxation system. You can apply tax rules and it will be added to the product. Sellers don't need to take care of it. You just need to create the correct taxation rules to make everything work.
11. Yes, You can choose any of our templates. 1 template comes complimentary with Lifetime Plan.
12. Yes, Sellacious has a dedicated section for that. They can even set different policies for different products.
13. These add-ons work with SP Page builder. You just need to download a plugin and use SP Page Builder to create page templates.