I'm working on new technologies to assist in child education, mostly in developing countries, and I was wondering how difficult will it be to integrate voice feedback into a mobile application.

Let me give you an example:

Small phone-based application that upon calling an IVR and providing some login information (via the phone's keyboard), will present a text on the phone screen to be read by a student; the system will transmit the readout back to the IVR server to be analyzed later. This analysis will be the basis to evaluate the child's capacity for reading (which can be done either by a person or can be automated, but that's another discussion) and later reported via SMS, etc to the parents, teacher, school, etc.

I may not be able to just store the recording in the phone and transmit it later since:
a) There may not be a GPRS network available
b) It may be more expensive that recording the output to an IVR server

I would like to know:
a) Is this possible? Too ambitious?
b) Will I be able to update the application on-the-fly (i.e. with new text-to-be-read) if I have a GRPS network?
c) What kind of phone should I use? This will impact the cost of the phones, and ultimately the feasibility of this project. Can I use a Java-enabled V-180 or will I need a "heavy" platform as the Treo?

If you have any experience I will appreciate if you can provide me with some pointers as to start my investigation.

Best wishes,