Re: Jo kismat mein ho ga
To understand free-will/pre-written thing, think of a teacher student scenario.
Most the teachers can tell before exam (and probably give in writing - hint hint pre-written) who will do good in exam, who will do average and who will fail. Is it because of this that students still fail? NO. They fail because they do not work hard enough but most of the time teacher can tell in advance.
"Jo qismat main ho ga" has a pre-condition of working for it. Its more of after working hard and doing your own part, jo qismat main ho ga wo mil jayee ga. Two people who are working equal hours and equally hard do not always get same return. Its more applicable in this scenario and not in scenario of not working for it.