One way to setup a vApp so the local scope IP's will not change. (Keep in mind the NAT IP will change, but that is normally only used for training systems to get a RDP session in)
Add each VM to the vapp
Add a VApp network to the vapp
Set the parent connection for the vapp network to your normal network
For each VM in the vapp connect them to the vapp network
Set the static IP you would like for each VM
Boot the vapp to make sure all is well
If all is well add to catalog but MAKE SURE to select "Make Identical Copy"
At this point you can spin up many of this same kit, each will get a new NAT IP (used for RDP ect) - but the internal IP's will stay, so your kit will work. (Just keep in mind VMs in your vApp should only be talking to each other on the internal IP)
Hope that gets you going, if you get stuck just let us know.