Sending multiple electrical signal to PC via Serial port

I am doing a project in which I want to control small toy car using EMG signals from my forearm. I want to send 4 electrical signals to the computer. I have made a processing circuit which contains amplifier, filter and ADC.

My question is,

1. How can I send 4 signals to the computer using serial to usb cable?
2. Is there any alternative with which I can send these signals to the computer more easily?