Tier 2 ICT and Offered Job in UK

[Sunshine Rise]

Hello All,

I am staying in UK in a Tier 2 ICT Visa from July 2015 in Company A.
My Visa is valid up to September, 2018.
I have been offered a job in UK payroll by my present employer. ( Company A)
My query is :-

a) Can I join in a UK payroll in an ICT Visa ?
b) As rules changed from 2011, does that mean I can start working as UK Employee in an ICT Visa for another 2 years and then have to go back to serve 1 Year Cooling off period and apply for Tier 2 General.
c) Does Cooling Off Period means any country outside UK or does it needs to be the Home Country ?
d) If answer to (a) is No, then does it means I need to wait 1 year cooling Off period unless I can join the new position in UK ?