Something I want to know is how many transactions of less than $100, less than $50, less than $5 and less than $1 does visa handle on average per day.

As a consumer I dont care how long the visa portion of the checkout process takes either as Im bogged down by several seconds of either POS prompts, or manually entering card number, expiration and a 3 digit security code. That is to say my user experience is that a visa transaction takes about 10-20 seconds.