Tier 2 General maternity related info

[woodie]

Hi
I have a question regarding 'maternity' leave on tier 2 general for my wife. Here are the details
Job Joined: May 2015
Switched from Tier 2 ICT Dependent to Tier 2 General: October 2015
Tier 2 General Visa end date: October 2018
Due Date: November 2016 (8 months from today i.e. March 2016)
I am currently on Tier 2 ICT visa valid until Oct 2017.

Question:
1/ When should she inform her employer? Is it advisable to inform earliest or can inform the employer after first trimester?
2/ Is she entitled for statutory 52 weeks maternity leave?
3/ If she can take 52 week maternity leave is there any issue with Tier 2 General Visa and leading upto ILR? she will stay in UK only for delivery, maybe go to home country for 3 weeks maximum.
4/ Can she be made redundant a) after she inform her employer? b) during her maternity leave? and in this case what happens to her visa and living status in UK, does she have to go back?
5/ Can I switch to her dependent when she is on Maternity leave?

Thanks & kind regards