ILR for Work permit holder same day service

[Vir]

Hi,
I am on work permit, nearing to complete 5 years. Some questions in my mind,
1) Work Permit issued on 13/01/2009, visa stamped on passport on 26/02/2009 and expires on 25/02/2014. Entered in UK on 8/03/2009. What is the earliest date I can apply for ILR? I mean the 28 days before will be counted from 25/02/2014 or 8/3/2014?
2) Am I eligible to apply at PEO for ILR? I checked the ukba site, there they mention about all point base categories, but I cant find anything about work permit holders. Is that mean the premium service is not available for work permit holders and I have to apply by post only?
3) About employee ref letter --- I was working for the same company since 2007 on dependent visa and then changed my visa to work permit on the above mentioned(in point no 1) date. So in the ref letter from employer, what date of joining( ie. the XXX employee is working from DD/MM/YYYY with us) should be mentioned? Is it ok to mention the date from 2007 or I need to put the date of 8/3/2009( the date on which I enter UK with my work permit)? Pl. note during this changeover of visa, I was still on the payroll and been paid.
Your valuable guidance will be highly appreciated.
Thanks
Vir