Hi Shanthsuren
for your first question, according to the requirement of immi web, to be eligible for the visa, as listed
have been nominated by an approved Australian employer for a job in regional Australia (regional Australia does not include the Gold Coast, Brisbane, Newcastle, Sydney, Wollongong or Melbourne)
are younger than 50 years of age, unless you are exempt
meet the skills, qualifications and English language requirements, unless you are exempt
apply under the stream for which you were nominated.
For second question,
you don't need to complete skill assessment, the company need to give you at least two year full time contract and nominate you for 187 visa.