Tier 1 General ILR, Economic activity& Continuos stay

Tier 1 General ILR Application:

I got my T1 General Visa on 17 October 2010, first entered the UK on 11 November 2010. Since then I was in and out the UK for many times. I'm planning to apply for ILR next year and I'm very confused about the following:

1- First question, I don't remember when did I leave the Uk as I'm almost traveling to my home country for work every month and my passport is full of stamps and the UKBA doesn't stamp the passport on departures, so I don't know when did I leave the UK and I can't calculate my absence periods accurately.

2- Second question, it took me a year after I got my visa to form a company and took me another year to start the actual work and another year to have regular expenses from my bank account as I moved permanently with my family to live in the UK in 2013. I couldn't find any requirements for economic history in the SET O guidance. Do I still qualify for ILR, what are the documents required to prove my economic activity? Do I have to supply this? I started receiving salary in 2012 (2 years after I got my visa). What are the documents for the economic activity and do I need to present any? I'm planning to apply with Premium service.

Please help, thanks
Sam74u

Look forward to reading responses to this one, as one of my friends is in a similar situation