If you are not using CARP type VIPs, then the IPs will not be pingable.
Look at the wiki-page to VIPs for more information.
You dont need to do anything (like creating a 1:1 forward) for the VIP to function.
The VIP will bind to the interface on which you create it --> Not necessarily on WAN.
You set the subnet on the same page on which you create the VIP.
You can use CARP-VIPs even if you dont need CARP functionality.
If you set up a VIP (any type) and forward stuff from it (and allow it with firewall rules) to a server behind it should just work.
I'm not sure i understood what your problem was.
Did you test from the outside? Did you try to access it from within your LAN?
Did you look at the pfSense wiki ( http://doc.pfsense.org
There are quite a few howtos.