The CSS is only really going to be presenting the VIP addresses to the external access traffic. You can still connect to the internal IPs of your servers as long as you have a route directly there, otherwise you cannot directly access the individual servers through the VIP without lots of work (like fiddling with cookies when doing cookie LB to rig which server you reach).
Usually, you just connect to the servers on their direct IP addresses, and let external traffic and DNS point normal application traffic at the servers through the CSS front-end.
The outbound access works differently based on how the CSS is setup. Sometimes, you want to pool servers behind one nat address on the CSS and present them that way (for outbound). Sometimes, you have the servers setup for DSR where they return to the internet through their default gw (when it isn't the CSS). There are many ways to configure this, but those are two of the most common.
Make sense?