Forwarding to cell phone only from extension dial not queue group

I have an IVR when you dial in to the main DID that allows the selection of 5 options as well as being able to dial an extension directly. The 5 selections are queue groups that ring at various combinations of 6 phones. My extension is 400 and rings from queue groups 1 and 4 so the 3 ways to get a hold of me or someone in my department is by dialing 1, 4, or 400.

What I desire from the behaviour is if someone dials 1 or 4, it rings at my desk phone 400 as well as the other phones on queue groups 1 and 4. When someone dials 400, I want it to ring at my desk phone for x seconds and then forward to my cell phone. This is so if I am in the office I can grab any call, but if I am out of the office and someone is trying to call me specifically, it would ring at my cell phone (after a small delay).

I have tried call forwarding but it forwards all calls to my cell phone from queue 1 and 4 as well as my extension 400. I have tried creating my cell phone as my voicemail so it forwards after a certain delay but still queue groups 1 and 4 ring at my cell phone.

I looked at Follow Me but want the ring time to be 6 seconds at the desk and then ring at my cell but only with calls directly to 400.

Another thing although likely not as easy of a fix would be when my cell phone rings it appears as if the office DID is calling me, not whoever is calling in (as its being forwarded from the FreePBX system). Any way to have it come in as a modified number ?