Please advise on the easiest learning path, as well as simple mocking library to start with.
Try Stephen Walther's excellent article here:
http://stephenwalther.com/blog/archive/2008/03/23/tdd-introduction-to-rhino-mocks.aspx
EDIT: And I would advise that you do start with Rhino mocks as it does seem to the be the current defacto standard.
I would strongly recommend using Rhino Mocks. It is, in my opinion, the best and easiest to use mocking framework out there.
It has support for the Arrange-Act-Assert syntax which for me is the most logical way of setting up and using your mock objects. This article is a decent primer on how to use it.
I'm actually trying to get up to speed with mocking myself, and I've found that MOQ seems to be a little more intuitive than Rhino Mocks (if you're comfortable with lamdas and are using .NET 3.5).
Phil Haack compairing MOQ with Rhino Mocks: http://haacked.com/archive/2008/03/23/comparing-moq-to-rhino-mocks.aspx
Quick Start page on Google Code: http://code.google.com/p/moq/wiki/QuickStart
string mockingStatement = "You've got a face like a bulldog licking p!ss off a nettle!";
Response.Write(mockingStatement);
string
mocking_statement = "Your mother is an hamster and your father smells of elderberries!";
Response.Write (mocking_statement);
Skizz