Clarification on Category A or B

1) Which category would you apply under if you have two jobs

Job 1 you have been employed since 2009 continuously and earning £7.30 per hour for 30 hours per week
Job 2 you have been employed since Nov 2013 - so not yet 6 months

Can you rely on category A?

2) If relying on Category A and you have 6 months payslips but the salary varies is this still ok? Because in December the company paid salaries early so money was less. Then in January the company paid the shortfall plus usually salary so the total salary is more.

It would be Cat A once employed in the 2nd job for 6 months.
Are both jobs paid by the hour? If so, then the calculation for non salaried employment can be used which is the average over 6 months, rather than having to earn a set amount. So as long as on average you have earned £9300+ you're fine.

You may be able to apply under Cat B if you do not meet the requirements for Cat B. See also, Annex FM 1.7 (click).

Is the employer letter always needed in every application and does it have to state ALL of the required info?

The employer in this cases has written £14,000 is contractual salary even though he earned £20,000 in the last 12 months with overtime and he's relying on category B.

He is afraid to submit the employer letter