Legal issues with an NDA that I do not want to sign [closed]

Question

I've been given a non-disclosure agreement (NDA) to sign by my current employer that I do not want to sign. It is incredibly open ended and I feel that it should have been a condition of my initial employment agreement, which I signed three weeks ago.

The document contains very many definitions in the form of "including but not limited to," and "directly or indirectly."

As well, it states that:

• I agree that any breach of the contract would inflict irreparable harm on the company (I agree that a breach may result in harm to the company but not necessarily irreparable harm).
• Should the document be amended any time in the future and I refuse to sign the amendment that I would be in violation of its terms.
• Everything I develop while under the company's employment is its property (neglecting to say whether what I develop on my own time, distinctly from my work, is my own).
• After my employment ends at the company I would be required to continue my duties there to assist in the perfection of its software, that I would not be allowed to perform any duties directly or indirectly related to my duties there for one year after my employment at the company ends (would I not be allowed to engineer software for a year?).
• Should the company decide to prosecute me for breach of contract that I agree not to defend myself, and that all terms in the document would be transferred to any company which purchases the one I work for without my consent.

In short, they would legally own me for life and could absolutely destroy me for any reason they deemed fit.

Are there any legal arguments that I could use to defend myself against signing the contract? For example, the fact that the NDA was not part of my initial employment agreement or that the document is intentionally abstract and vague to allow them to fill in the blanks any way they please?

The company hosts the entirety of its source code on a site which employs a publicly accessible SCM and greatly embraces open source software — the chances that I would ever come in contact with information that could legally be considered a "trade secret" or "confidential information" is very slim, so why would I need to sign the NDA? I do not believe that many of the employees there actually took the time to understand the NDA before they signed it, and know for a fact that a few of them did not.

Are the terms of this agreement commonplace among the software engineering community?