Can the the rate of the flow of electrons (current) remain the same even though the number of coulombs differ?
If current is the rate of which charge flows, do speeds of the
  electrons matter on how many they are.


Does the speed of 50 cars driving down a road affect the number of cars passing down the road?


  For example, can't a group of 0.5 coulombs of charge flow as fast a 1
  coulomb of charge?


Electrons have a varying speed but it's the number of electrons that pass per second that dictates current.


  Why is current dependent on the number of coulombs?


Because current IS the rate of change of charge, dQ/dt


  It's kinda like a drop of water running down a pipe as fast as a
  stream of water. So what really is current....?


It's the rate of change of charge, dQ/dt


  And since voltage is proportional to current, does that mean it is
  also proportional to charge


I hear the sound of a can of worms being opened....

Energy (W) = \$\dfrac{CV^2}{2}\$ for a capacitor
But we also know that Q=CV therefore we can re-write the energy equation as: -

$$W = \dfrac{CQ^2}{2C^2}$$

If we then differentiate to find rate of change of energy with respect to charge we get: -

$$\dfrac{dW}{dQ} = \dfrac{Q}{C}=V$$

Voltage is much harder to put your finger on but in words.....

It's the rate of change of energy with respect to charge


Just as the velocity of a moving mass....

Is the rate of change of energy with respect to momentum