Hello.
I would say don't assume that you can get a job the same time frame from someone that you may know or have read in this forum or others. Applying for jobs in Australia is competitive as well as in some countries. Just because Australia is offering an opportunity for workers to come live and work in the country doesn't necessarily mean there is a job for every worker. What I mean by this is, you may have the skills/education the company is looking for. However, there are other applicants with the same skills/education as well. As 2Curlews mentioned in his post, it looks like there are about 100+ applicants for an avg job position.
In regards to your question about salaries, in order to work in Australia, you have to have the specific work visa required. You should be able to get the salary that is being offered in the job posting. Some job postings have a range depending on your work experience and could be dependent on # of years. Some companies already have a salary range set up according to # of years,etc. Of course, this varies from company to company. You can search in the internet with finding out what the avg salaries are for specific job positions in Australia.
The salary that you may be offered in Australia might be higher than what you are used to depending what country you are coming from. However, keep in mind that the cost of living in Australia is one of highest compared to other countries. You would need to make sure the salary you are being offered, you can support your family in Australia. Once you know what your net salary after taxes would be, it will give you a better judgment if you could support your family in Australia.
Check out immi.gov.au for more information about the visa you can be qualified to apply for. In addition, check out the career websites: mycareer.com.au, seek.com.au, expateng.net
From what I've seen about job postings regarding engineering, the industries with the most postings that I saw were from mining and construction industries. That was under product/project engineer. Not sure about process engineering.
I hope what I stated will not discourage you from considering Australia. You will just need to do further research in determining if your education and skills are recognized in Australia. If you are not sponsored by a company, you can sponsor yourself by applying for the visa 175 (skilled independent ) from immi.gov.au website. But you must meet all requirements and reach the specific point system required. If you do, the first step is to get your skills and education reviewed by Engineers Australia which there is a fee to have done. Only when they evaluate your credentials and confirm it is recognized in Australia can you apply for this visa. Without this approval, you will not be able to apply for visa 175.