Yes, you're allowed to integrate adsense on an Amazon review site. Whether or not it will work or if it's a good idea is an entirely different story and completely dependent upon your site.

Not necessarily, but it really depends on what you're promoting. Electronics, for example, is typically a high-paying topic when it comes to AdSense but something like books won't really give you anything more than a cent per click, if that. And then there's this line of thinking: do you want to give your visitors the opportunity to click on something that's not related to your Amazon product? If you're in a high-paying AdSense niche, it might be OK, but otherwise you're potentially throwing away a sale.

Yeah you can use Adsense on a review website and sometimes it is actually worth it because the CPC can be pretty decent and you can increase your monthly earnings. Just choose the right products to review and target high paying keywords.

I agree with dadamson, when user landed on you review site, those might landed from buyer keyword search on google.com. Those might click on the adsense than the affiliate link.

If your site have a lot of visitor but minimum affiliate review conversion sales, put the adsense code.