employer's evidence for I-140

I am going to prepare I-140 on behalf of my employer( without hiring an attoney),for ability to pay wage, the instructions of I-140 are copies of annual reports,federal tax returns, or audited financial statements,
1.which one ?
or all of them? how many years of annual reports must be included?
2.any other evidence from employer except a letter from the employer? please remind me.

Also, since I will file I-140/I485 concurrently,
1.what's the definition of I-485 pending, after I-140 approval or the date filed concurrently?
2.some people said EAD can filed together, Can I file later with yhe recieved notice of I-140/I485? I want to use H1B1 before it expires. Please advise.

I appreciate your opinions and help.