We do but most people will not want every invoice in both Nexudus and Xero. Nexudus is pretty good at handling all your account receivables (invoices and payments) and you can get a good number of finance reports which can group revenue in any way you want so you can simply import this revenue reports in Xero at the end of the month. For more details, see Xero.
When setting up an event you can add a ticket URL, which can point anywhere, including EB. You can also sell tickets directly on Nexudus if you wish to do. You can link your ticket prices and availability to the different price plans.
If the user is signed up to a plan that provides them with passes, make sure that the passes are enabled for the plan. If not, the platform will send an error message.
You can connect Nexudus to MailChimp using Zapier: https://zapier.com/developer/invite/12046/632a0de40dee0d7a63f951bcaec7df79/ For more information, see Setting up Zapier.
There is a basic integration with Slack via Zapier, a platform that allows you to connect different apps.
For the apps that Nexudus does not integrate with by default, we have a REST API that you can use to create apps linked with your Nexudus account or connect it with services. You can find more detailed information about the API in the developers hub.
Customers set up as companies cannot use Papercut, only customers set as individuals may use the Papercut integration.