Help in estimation from 3D experts

[gagandeepb]

Hi Guys,

I am new in 3D game development and openGL and gone through SMourice tutorials given in this forum. I have to work on one project where we are planning to move 4 3D characters in a city. These characters will be on vehicles and will perform some tasks.
I just want help in estimation.

(1) How much will be the learning curve. (1 or 2 Month) ?
(2) Is it possible to develop this game in openGL ES or i should go with Unity?

As per my background i have 3 year experience in .NET,C#,ASP.NET and i am working on IPhone since last 1 year (UIKit,CoreLocation, Mapkit, Network framewwork) and worked up on 7-8 applications on IPhone with almost all UI controls.

Thanks,
Gagandeep