Coffee

Around 100-130mg.

Both? It starts affecting you (being used up) and is starting to be broken down right away after you drink it. Not all gets used right away and not all is broken down right away, so it stays in your system for a while, circulating in your bloodstream waiting for a receptive site to bind to, or for the liver to catch it and break it down.

If you were to get this much caffeine from drip you'd have to drink 1.5-2ish cups. That takes time, which both attenuates the spike, and also extends the time the caffeine will effect you - at least by the time it takes you to down those cups.

So, the benefits of a double shot of espresso is that all that caffeine gets into your system quick, so a higher spike, but relatively shorter duration. Benefit of drip, somewhat lower spike but relatively longer duration - driven not as much by residuals in your bloodstream but by a longer titer.

Cool graph of caffeine plasma concentrations over time by various doses here.

1. About the right amount.
2. Cumulative. I feel my lifetime total of 10’s of thousands of cups racing through my veins!

1. about double the caffeine than what is found in a single shot of espresso.
2. its concurrent, if you drink 100 cups of coffee that has 1mg of caffeine you will have 1mg of caffeine in your system. However if you drink a big cup of coffee with 100mg of caffeine in it, you will have 100mg of caffeine in your system.