I would like to join the Affiliate program of Amazon and I am wondering, if the comissions are paid only for the products sold and shipped by Amazon itself or if I can "link" also to the products of the "hosted" vendors (like: "Sold and shipped by xxx")?
Yes, you get advertising fees for third party (as they now call them) products.
What are the referral-fee rates for third-party items?
You earn from 4% to 10%, depending on your shipped items volume, under the Performance plan. […] Third-party items are defined as any product sold by a third-party seller on our site, as long as it is not an Auctions or zShops item. Products sold by third parties through sites linked to from our site, e.g., Shutterfly.com, are also excluded.
Yes, you get advertising fees for marketplace products.
Auf welche Preise stützt sich die Werbekostenerstattung?
Sie erhalten eine Werbekostenerstattung auf den von Amazon.de bzw. dem Marketplace-Anbieter tatsächlich berechneten Nettoverkaufspreis des jeweiligen Artikels. […]
For other Amazon sites
As every Amazon site (per country) has an own affiliate program, it’s theoretically possible that terms differ.