My website has featured products section on the front page and in this section, we rotate 4 products everytime the page is refreshed. I am wondering if this has any negative effect for SEO since I read somewhere that if the link on a certain page keep on changing, it will have a certain effect? Thanks in advanced for your help.
This is absolutely fine. Basically if your site needs it you can use the rotator. I have seen many sites doing this and it does not have any impact with SE's.
This is good to do. It helps when the SE bots come to your site and see new content on the site. I would even update the sitemap.xml file to reflect the homepage updates daily as result as each time the homepage is indexed new content will be available. Will also slightly help in getting the product URLs indexed quicker on your site.