Extension for Tier 2 over 7 years in the UK

[Umaraja]

Hi,
I want to know if I can extend my stay in the UK on Tier 2 as I've been in the UK for over 7 years. I entered UK in Sep 2008 as a student and then switched to Tier 1 PSW, following which I applied for Tier 2 in March 2012. However, my visa got refused because of an office error in entering wrong salary on CoS, and I went to the court with the correct information. I was granted Tier 2 after the appeal in August 2012, but received the passport only in Mar 2013. Please answer
1. When does my Tier 2 for ILR start, is it March 2012(application date) or August 2012(appeal win date) or April 2013 (received Biometric).
2. Can I extend my Tier 2 in Nov 2016 as I would have lived in the UK for over 8 years at that point. (UKBA states "You can apply to extend your visa for up to another 5 years, as long as your total stay is not more than 6 years.")
3. If I become my partner's dependant on Tier 2, will it be counted towards my 10 year settlement?
4. Am I allowed to move to a different category in Tier 2 such as Minister of Religion?

TIA