There are exit nodes in i2p, but they are called outproxies. The most popular ones are exit.stormycloud.i2p
, purokishi.i2p
, and outproxy.acetone.i2p
. To setup an outproxy, you will have to setup software external to i2p, i2p routers by themselves will never exit. It is possible to visit onion domains inside of i2p, StormyClouds's outproxy has support for this, but from what ive heard, its recommended to use none of these, and to just use the tor browser if you need to access onion sites or the clearnet anonymously.
There are many use cases for i2p besides eepsites and torrenting, pretty much anything that runs on TCP can prolly be ran on i2p. For example, I run my servers ssh over i2p, so if my ip address were to change for whatever reason, the i2p address will remain the same. There are also IRC services, internet radio stations, there are even 2 public Minecraft servers.