You mentioned that the reviews will be started by "a staffer or by a community member". Do you plan to have a full-time staff running the site/business? Also, where will the community members come from? In other words, how will you advertise the site in order to get people to sign up as "community members"?
Just a thought - it might be helpful to limit the reviews to certain types of products in the beginning, until you get the site up and running. That way you can focus your advertising efforts more efficiently. Since you mentioned Amazon, I will use books as an example. If you limit the reviews to books, you will be able to narrow your advertising efforts to avid readers. The site will also look more relevant (and appealing) if it has 100 book reviews, rather than 10 book reviews and 5 car reviews and 20 software reviews. After you have established a following you can gradually add other categories and build on your previous success.
For micro-loans, you might check-out www.prosper.com. It`s basically a peer-based lending model. I haven`t tried it yet, but I know the model has been very successful in the UK.