Hi Shivaj,
I am a little confused what question you need an answer.
My first question for you would, did you visit immi.gov.au to obtain more information about how to apply for the Visa 175 and what requirements you need?
The requirements have changed since I last looked at the information and it has become more restrictive in the requirements since 2010.
You didn't mention in your post, but have you already visited your particular assessing authority organization in regards to your profession? For example, if you are in engineering, you will need to visit the website of Engineers Australia to know what you need to submit to have your skills and education evaluated to determine if it is recognized in Australia. You have to pay to have your information assessed. After they assess your skills and education, they will send you a letter to let you know if your skills and education are recognized in Australia. This letter will have a reference number that you will need to enter in your application. If you receive a letter stating that your skills and education are not recognized in Australia, you will not be able to apply for this Visa 175. The assessing authority will probably let you know why or what you need to do in order to get approval. In using the occupation like engineering, Engineers Australia only is interested in evaluating the bachelor's degree. They did not request for any information for post graduate. This might be different for other occupations such as medical doctor,etc.
According to the requirements for the Visa 175, you need to have a total of 65 points for your application to be evaluated. If you have less than 65 points, then your application will be refused. This is documented in the points section in the Visa 175 section in immi.gov.au However, at anytime, the points can change depending what the Australia Immigration decides.
Look at the points system and find out if you will have 65 points in total. If you don't and proceed in applying, the fee for applying is non-refundable.
If you meet the 65 points and decide to proceed in applying, you will need to provide proof of employment and certified copies/company logo documentation - pay stub, bank statements, tax records,etc. for a certain number of years that is stated in the Visa 175 requirements. No Australian Immigration officer will be contacting your employer to verify information. You as the applicant will need to provide the required documents. Once the immigration officer has received all your required documents, then they will determine if they will approve you. If you have vague information and is not as detailed, your chances of getting approved might not be good. However, just because you meet all the requirements does not mean you will get approved. It will be up to the immigration officers that will evaluate your application if you will get approved or not.
There are many other requirements that I have not mentioned above. But only referencing a few of the documents you stated below.
If your company does not provide the required information, then does that mean when you apply for house or car loan, the banks have to contact your employer directly? In the US, we usually just provide a copy of some of our paystubs, tax documentation, or bank statement. Contact your human resources department for help. If you state what you need the documentation for, they should not be able to deter you from getting that information.