I have an ethernet handoff coming from my provider. They have provided a /30 for the link to their router and then a /25 block for my use. Generally I would terminate the /30 link with a router. However, can I terminate that /30 link on my ASA and still NAT my usable block as if it resided on the outside interface?
You can do that as long as those ranges are being sent by your ISP. Unfortunately, the ASA is not designed for high-speed routing, so you will see a performance difference between the ASA and the router.