Hope someone will correct me if I'm wrong:
1. My partner is pregnant & she is on maternity leave. I would like to know for how long she can be on maternity leave?
http://www.adviceguide.org.uk/england/w ... _leave.htm
gives a good idea about it. I regard a woman on a maternity leave as a worker as she is still under a contract of employment and therefore satisfies the Regulations as a qualified person.
2. I was being told I should have CSI etc from the date my partner goes on maternity leave. What is CSI? My partner is getting payslips from her work mentioning her maternity leave amount.
that is wrong if my 1. assumption is right (and it must be right as your wife is being paid while on leave for the first 26 weeks);
3. After maternity leave is over, Can my partner work part time to exercise her rights. How many minimum hours she has to work?
The term "work" includes ANY work which is "genuine and effective". Therefore there is no clear rule as to how many hours one has to do. I had one person who worked 12 hours in a supermarket and noone mentioned anything at the UKBA as the work was regular, genuine and effective. There even was a suggestion in one of the cases that 10 hours a week is absolutely fine to be regarded a worker. What is not regarded a genuine work is where there is no contract of employment and you are, for instance, stacking shelves in your uncle's shop, helping out occasionally etc.
4. If she chooses to study to exercise her rights. Can it be part time course like once in a month class. Can she go for any certificate or diploma course rather than degree course? can it be a course from open university?
The point with studying is that, whether she is studying or not, all the family members (even those non-EEAs working) have to have a sickness insurance CSI, so if you think that studying is a good way of exercising treaty rights just for the sake of it, you're wrong. I would suggest going for the self-sufficient category where you do not claim any benefits and have CSI. But by that time she can surely have a part-time easy job until you get your PR.
Good luck and congratulations on having a baby on the way!!!!!!!!