Formal letter (with a potential employer)

You cannot write such formal letters with this kind of tone.  To a native speaker, it smacks of haughtiness as if the company is begging you to work for them.  Even if the grammar is perfect, this will definitely make the potential employer think twice in hiring you.  I know English is not your native tongue...  So I am rewriting your letter entirely while maintaining the intent.

Dear Sir, Madam if you know it is a lady.

I am most grateful in receiving your letter of intent to be on board with your engineering team. Before coming aboard, I would be like to know more of the project's specifics that I am responsible for. It was was not discussed in detail during the interview.  You need to have this or some other reason like it was not discussed at all in the interview etc; otherwise it only shows that you were not attentive in it.  Now this will be bad...

I thank you again for your consideration and confidence in me.  I look forward in coming aboard.

Sincerely,

Dear …
thank you for your letter. (It’s great to hear from you!)

I'm still open to engineering job and the offer is really great.
But before I will agree could you please introduce some basics of the project: papers, tasks that have to be solved,...

Looking forward to your reply!
Best regards

Formal letter (with a potential employer)

Dear …
thank you for your letter. (It’s great to hear from you!)

I am still open to the engineering job and your offer is fantastic.
 Before I accept your offer could you please introduce me to some of the basic principles of the job: papers, tasks that have to be solved,...

Looking forward to your reply!
Yours faithfully

the first bit is a little informal maybe with the exclamation mark, also when writing formally try to limit apostrophes (') eg is not not isn't