If a resistor acts to slow current then how can the current in a series circuit be the same through multiple resistors - Won't the current go down and be lower after each subsequent resistor?

No. A resistor doesn't slow down the speed of the current, it limits how much can flow. Current can only flow if there is a complete circuit. The curent flows from the negative terminal of the power supply, through the load (resistors, lamps, or whatever), back through the positive terminal. The same number of electrons that leave the negative terminal must return through the positive terminal, so the current must be the same anywhere in a series circuit. More resistance just limits the current more. Think of a single file line of people, standing so close to each other they are touching, trying to squeeze through a series of narrow openings. Each opening slows the line down a bit, but the same number of people that enter the line also come out at the other end. Since a person can't move until the one in front of him does, the number of people passing any particular point every second is the same no matter where you check. The more restrictions (resistance), the fewer people per second. Make sense?