Stepper vs servo or DC motor
Are you in mechatronics? I've used steppers in direct drive applications with some success. You can avoid most missed step events by driving them carefully, i.e. writing good code and implementing proper acceleration profiles + doing micro stepping when necessary to decrease torque ripple.

Having said all that, You should stick to a continuous rotation servo, or either of direct or geared drive through a DC motor for your project. You will draw less current, almost certainly, for a given speed. You will save the headache of writing a lot of extra code to get your steppers working optimally. In short, you don't want to have to worry about the particulars of using steppers if you also need to worry about the bigger picture, which is getting your project done well.