Don't worry, no extra costs for basic settings. Here are the procedures for self-hosted setup.

In order to get messenger work, you've got two options. Either you follow the instructions in the Wiki for setting up your own Jot Server. That little server is needed to process the messages. But to do so, you need basic server system knowledge and access to the root of your hosting server and some other complicated stuff, like server certificates and opening the communication port on your server and probably in the firewall of your server. If both do not hold true for you, then there is the easy way, which I prefer as well, to use MSolutions Jot Server on jotserver.com. There's even a free subscription option, to get started with messaging without additional costs. All the needed setup work has to be done in Studio -> Messenger.

As to your second request, Push Notifications, first of all you need to sign up on OneSignal.com for a free account. As soon as you are registered, it's very easy to set up your site for push notifications. As soon as you've successfully configured your site for push notifications on OneSignal, you'll get the necessary API keys for the further setup of OneSignal in Studio -> Settings -> Push Notifications. In that form you fill in the necessary setup info from your OneSignal site account, and voilà!

Here's the procedure for UNA cloud hosted setup.

Write a message to support@una.io. 😉

If you get stuck somewhere with your configuration, either post it here, again or write to support@una.io and you'll get the best support you can ask for.

Edit: And don't forget to use this excellent search module here on the UNA plattform 😉