Yes, recently a free version of WC Affiliate has been released.
Yes, WC Affiliate lets your affiliates apply discounts on their referral links. You need to enable discounts from the Basic settings in order to let your users apply discounts on their affiliate links.
Yes, with WC Affiliate users can create custom referral links within seconds. You can choose from random shortlinks or user defined shortlinks as well.
Yes, WC Affiliate has the option to customize all the emails to keep your users updated. You can set your own message for Affiliate Application, Account Approved, Account Reject, Request Payout, and Add Credit in the Email tab of the Basic Settings.