Radios list are read directly from Live Stream SII files. To manage them, flag the radio you want to see here as favourite then click on the 'Update Radios List' button
If the job added caused an economy reset and you have been teleported to your base garage, you are adding a job that is not permitted or is not spawn-able
From here you can hire a new Mechanic. Each Mechanich have a precise set of skills and can take care of a specific maintenance type. Furthermore, they have a speed which means a decrease of 5% for each speed point in maintenance time