Help with the ILR application-5 yrs work permit holder

[customer_s]

Hi everyone, here is the story.

My mum was rejected for ILR last December because her salary didn't meet the new rate criteria (Code Of Practice). After negotiating with her boss, she was agreed to pay the minimum rate on COP, and it's been three months now. She wants to make a fresh application.

Here are my big concerns and wish someone in this magic forum can help me:

1. In the past 5 years, the amount she got paid shown in her P60 didn't reach the the salary stated in her work permit (around 1000-2000 less each year), will this be a big problem to her ILR application?

2. Her current rate is nearly 50% increasing. Does her boss have to write a letter and explain the reason? and again will this be a big problem to the application?

3. She was struggling with the cohabitation documents.(My dad is going to apply for ILR the same time) After i read through the post:
http://www.immigrationboards.com/viewtopic.php?t=79378
My understanding is work permit holders don't have to prove 2 yrs' cohabitation, am i right?

4. She is planning to use the premium service but she is not confident with her spoken English. Can she bring me as an interpreter?

I wish anyone who have similar experience or have good understanding of immigration rule can help me out! Big thanks!

[customer_s]

anyone who can help? T_T