I got it all figured out, finally!
I am able to set callerID thru Link2Voip by creating an additional SIP username with whatever ID I want and set "LINE 1" to register using those credentials. I can't change it on the fly as I can with Asterisk tho, which means eventually I'll be setting up a dedicated box, but this will suffice for now.
To get the HotDialing set up, I mostly followed the instructions here
with the addition of changing some FXO Timer ValuesPSTN Answer Delay: 3
<--- gives just enough time for caller ID to pass, setting to zero barely saves 1 sec off total dial timePSTN Dialing Delay: 0PSTN Ring Thru Delay: 0
<--- so that my attached phone rings as quickly as possible
I have the analog line forwarded to my mobile phone, and then changed all my mobile phone call forwarding to various numbers that answer with "Due to Network trouble..." etc. from This is a Recording
My next project is either to hack the firmware or find someway to pass a variable to change id on the fly.