@dr.ew888 hello, welcome to the forum.
2- requirement for assessment is to have competent English. never read anywhere such exemption.
3 - you can only nominate 1 occupation. if you change nominated occupation it requires you have a new assessment. the previous assessment will be considered void once you nominate new one.
4 depends on your circumstances. like age u can get as high as 30 pts as long as you are not yet 33 y/o. skilled employment highest is 15 pts. ielts is max pts is 20. bachelor degree is 15.
5- its currently under red flagged occupation. they will closed it as soon as the supply of professionals under thoses occupation are more than enough.
PS please read the rule and regulation of the forum. posting to various thread of the same question is not allowed.