1 - Use part of the Amazon model to allow potential purchasers to ask the seller a question on the product versus a reviews system which is subjective and generally adds little value to a potential purchaser due to the inherent weaknesses in a review model.
Provides data to purchasers on what other purchasers wanted to know before purchase (e.g. framerates, ease of use, customization, how it was used) - creates eduction around the specific product to the potential purchaser.
Provides data to seller on how they can improve the product is a non subjective manner if features they don't support are asked for, or spin off products they may end up creating as a result of questions, or to improve upon their product.
Provides data to Linden Lab on potential feature requests is a product is limited by the platform it self. Create trend data to help inform how users are interacting etc.
Removes sock puppet/subjective review model that rarely influences purchasers and also may lead to poor reviews on a product in early days due to the immaturity of the platform when the doors open (inexperienced users misunderstanding use of a product versus real product issues).
2 - Consider how the Q and As will be answered. Just by seller, or by other purchasers (Amazon allows both). Perhaps make this selective by the seller so they can control in early days of a product release, but they may wish to expand to community answers as a product (and Sansar) matures.