Hi, Is it possible to replace the default rating option with a more advanced plugin?

Yes, that is possible if that more advanced 3rd party plugin can integration with Easydiscuss.

Also, is it possible to sort/display posts based on the rating received?

Currently that was not possible to sort by the higher rating first on the recent discussion listing page.

OK, thanks.

One follow-up question: do you have any recommendations for rating plugins that will work well with EasyDiscuss?

You're welcome

Currently I do not know which 3rd party plugin rating system can integration with Easydiscuss.

I am sorry that can't help much you here.