60 days leave to enter in work permit

[Etconfuse]

Hello,

I am being so confuse with uk ilr immigration and was wondering if anyone could help. Got sleepless nights as can't resolve the matter.
I am on uk work permit currently. Visa entry valid from 15feb 2008 to 15feb 2013. I entered on 28th feb 2008.
1) Am I right that with current rules, the earliest I can apply for uk settlement is in the 15th jan 2013?

I am from commonwealth country and as a visitor, I can live in this country for 6 months. Can I enter after the visa entry date which is 15th feb2013 and apply my ilr on 25th feb 2013? Can I actually enter the country during the period after visa expired but within 60 months from date to leave as typed in work permit issued by home office.

I would greatly appreciate your advice and feedback. My first time posting and please accept my apologies in case any errors. Many thanks.