Connect servo and dc motor to raspberry pi
DC motor (forward/backward functionality) should be controlled by H-bridge. There are a lot of ICs and PCB modules/boards for this purpose. Basically you can use any of them (depends on you DC motor parameters, of course).

Servo is not stepper. Servo is controlled by just 1 control pin by PWM frequency (digital pin), so you don't need any special IC or board for this.

So, you can connect H-bridge IC to several (4-6) digital pins of RPI, and servo to another PWM digital pin.