The only thing you need to prevent software updates from being installed is "upgradesoftware=false" in your bootpage. With this variable set software updates are still downloaded when available and your box will still reboot every night around 2am in order to install it but the actual installation will be skipped every time.
The "nothanks" patch prevents the 2am reboot, but without the "upgradesoftware=false" an accidental reboot will cause the software to install. So you need both if you want to disable the upgrade and the 2am reboots. Keep in mind though that if you wait too long to install a waiting upgrade your decryption keys will eventually become invalid and you'll stop getting guide updates.
The "ignoredrmsig" patches are not related to software upgrades. They cause the Tivo to ignore the signature on certain objects in MFS allowing you to selectively delete DRM objects without invalidating the recording.