I have some questions regarding wage and payment policy in the State of Washington. But first some background...

I am an appraiser working for a company who has no employee manual. The verbal agreement when I was hired was that the appraisers get paid a negotiated percentage of the appraisal fee. There is no salary or minimum wage...just a percentage split of the appraisal fee. The company (employer) provides an appraisal request to the employee, who then completes the appraisal and submits it to the employer for review. Upon satisfactory review the employer sends the appraisal to the client. Payment from the client may come 1-3 months after then employee completes the appraisal. Once the company receives payment from the client, the employee is paid, again 1-3 months after completing the work for the company.

Here are the questions:
1)Considering that the appraisers are W-2'd employees, is it legal for the employer to withhold payment to the employees (appraisers) until the client pays the company? It seems to me that the employee's contract is with the employer rather than the client and having completed the job for the employer the employee should be payed regardless of when the client chooses to pay the company.

2)Does Washington State Law require regular pay period for such an employee/employer relationship? For example, once per month? Should appraisals completed by the employee during this pay period be paid at this time?

3)If State employement laws exist which relate to the above questions, can a verbal contract legally exist which is in violation of these laws? For example, our verbal agreement is that the W-2'd employee is paid after the client pays the company. Is this an illegal practice despite the verbal agreement?

4)If an appriasal is not completed within the pay period must the employer pay at least minimum wage? For example, if I work on a large project that takes 2 months must I receive at least minimum wage until the project is complete?

Could you direct me to the source of any applicable laws. (i.e. WAC, RWC, L&I, ect.)