Database creation and conversion with billing feed into AS400

We are a transportation fleet management company, specializing in cleaning and maintaining transportation vessels. We currently maintain a database in Access and produce reports out of Access in regard to work and services performed. The process is very manual. From these reports, we manually complete billing report cards (BRC) per the customer's specifications (very detailed Excel spreadsheets detailing services performed and parts used). We then forward these BRC's to the customer for entry into their AS400 system for payment. Our goals: 1.) build a new database possibly using SQL or use the current Access version 2.) produce reports and bills directly from the database 3.) create the patch from our reporting to the AS400 billing schema 4.) allow for future customization 5.) possibly add a bar code feature to the system to eliminate field paperwork and additional data entry on the front end