Starting and running a retirement plan for your employees is a noble undertaking and a great perk or reward for you employees especially in a small business environment. However being a plan sponsor entails a lot of responsibility and knowledge of the mutual funds and investment market in general.
Unless that is the business you are in you probably wold be better off going in another direction. There is a point in the business size versus cost dynamic that makes it prudent to manage your employee 401K retirement plan in house but for now lets say you are in the category where it makes sense to farm out the management of the plan.
The most compelling reason to use an independent plan sponsor are The Employee Retirement Income Security Act of 1974 (ERISA) and the Internal Revenue Code (IRC) of which each has set forth specific requirements for employers to follow when administering and maintaining their employer-sponsored retirement plans. Keeping current with these items alone can be a full time job and one probably better suited to professionals in the retirement plan field.
You can hire an independent plan trustee to perform functions like the control and custody of the plans assets, trust accounting, as well as cash management. While the fiduciary responsibility is still yours, you now have a paid professional at your side to help in the fine details of plan administration.