How easy to set it all up?
Depends on where you're coming from. If you understand the underlying technologies that server/internet is based on then it should be pretty simple. If not that ranges from not so simple to near impossible.
I know I can do it all without Server, but I understand Server offers the GUI/easy setup of the DNS and such.
Most will find DNS the most difficult to deal with. I find OS X Server 10.6/10.7 far simpler to setup in Server Admin compared to 10.8 in Server.app. In 10.8 it's just not as obvious as it is in 10.6/10.7.
How is the built in mail server or should I look for a 3rd party?
It works well. There's not a lot to mail servers these days. Again, I find setting it up in Server Admin far better than in Server.app.
Is Appache the bear to set up as it looks like? (all the config files)
It's as difficult as any other Apache2 server config. Having said that, the 10.7 Server.app config is a bit of a pain when it comes to the shadow files for SSL/non-SSL as there's no clear and simple way to do them both for the same URI in the GUI. This is where 10.8 and 10.6 are better or simpler. That said there are not too difficult workarounds if you understand Apache config files.
