Akuhn,
The only way to have it follow another extensions programming is to turn that call into either a direct ring or transfer. Now that is not to say that it will be as easy as setting a manual forwarding path as you unfortunately figured out because the 5000 will ignore anything but an answer condition on a manual forward; we don't want call mistakenly answered by someone else basically.
So, the easiest soltution is to create a CRA that will Timeout to the extension you want to send the calls to and then forward all calls to that CRA; don't forget to remove the day and night default recording. This way the call is considered answered, by the CRA, and the now Transferred call can follow any other conditions applied to the phone you want to send the calls to.
Hopefully that answers you question for part 2.
Thanks,
TE