How to load entry-objects with Ajax
Is it best to use jQuery for the Ajax-request?`


Not necessarily. jQuery provides an easy-to-use ajax function, but nowadays it's perfectly simple to make an AJAX call with vanilla JS.


  How can I load the "next" five entries in a news-feed, so the call doesn't load the latest five entries over and over?


You will need to pass an offset and limit to your element query, or use Craft's paginate tag, in order to only receive data for one 'page' of elements at a time.


  I've seen that you need to build a specific template for ajax-calls. Is there any good examples of those?


I prefer to use the Element API plugin to serve up my JSON for front-end consumption... but you can also build a JSON feed using a Twig template.



Here are some links that might be helpful:


Basic intro info about AJAX
Tutorial on front-end lazy-loading with Craft ... (site appears offline at the moment, so you can also use a Wayback copy)
Element API plugin, which allows you to easily create a JSON feed of queried elements: 
Other answers from SE questions about AJAX pagination/loading