Hi Weaver!
I think the kind of functions you are looking for don't really feature in most home / consumer devices, largely to keep things simple for us normos out there. I think the vendors dumb down the firmware for a variety of reasons, keeping things simple and also to minimise the need for updates.
On the DHCP side, I have had a bunch of consumer routers and all I have ever really seen is enable / disable server, defining IP block ranges and IP reservation options. I have seen routers where you can define multiple DHCP IP ranges but I am not sure I have ever seen what you are referring to.
As you know I have a passing interest in DNS caching
from my thread here as I am having some DNS issues. I have yet to find (although it may well exist) a non-hacked consumer router tha has a DNS caching function without hacking the CLI and installing BusyBox addons - services are usually limited to choosing DNS servers and Dynamic DNS capability. One exception - I think my Zyxel VMG8924 router does allow you to set up DNS routes manually but not much else (I only use it as a modem though).
Both of the above observations are true of my current TP-Link TL-ER5120 which, by home standards, is a pretty complex dual-WAN device with a load of "Advanced" options.
I am obviously switching to pfSense shortly having assembled my DIY router, pfSense gives you an insane amount of configurability - which could be a plus or minus in my case
Chunks