Need assistance in building USB Micro-Controller

Hello - I need some help in building a micro-controller (uC) with two USB ports on it. One port (device) will communicate with a Window's based PC, the other USB (HOST) will have to communicate with a modem that has ONLY a device USB port on it.

I need to get a text file (notepad) off the PC onto the memory of the uC. It also must retain these values in case of a power loss.
The text/data file will be a list of variable and values and will be in the format;

variable: value

Once the data file is loaded on to the uC, it will be disconnected from the PC and will be a stand-alone device. The uC will then evaluate the variables that have values and send out AT COMMANDS to the modem.

For instance if the variable and value was

phone:925551212

then the uC would send out to the modem the following command;

atdt 9255551212

The exact AT commands that would be sent out is something that I would supply.

The uc must also send commands to the modem periodically to obtain the time as it can only send commands to the modem during certain intervals.

I do have a degree in electronic engineering and I have a CAD system, however I have long since been out of the design field. I can pretty much build anything if I have a schematic or application notes.

I just need a prototype for now - hanging wires or whatever won't bother me as I can always package it once it is proven that it works reliably.

This is garage kind of product on a garage kind of budget, however I am financially sound and responsible. I will pay for the job only - no hourly rate. 25% initial payment, 25% on demo, 50% on delivery.

Please let me know if you might have a solution or know if there exists one already. Also a rough idea of what this would cost would be greatly appreciated!

Thanks!!
Dennis