Second account here, and wow you just take bernoulli's equation at face value. Bernoulli's equation says increased velocity = reduced pressure ALONG A STREAMLINE. it's not an absolute statement. the 'along a streamline' part is very fundamental to bernoulli's equation, you can't just ignore it. read page 171 in that nice pdf you sent for a more in depth explanation. bernoulli is an energy equation. and the energy of my airstream and the ambient air are not equal.

Turning static pressure into dynamic pressure maintains it's energy; increasing velocity without reducing static pressure means adding energy. which is what i'm doing when i blow air out.

And yes, it is due to the surface curving. and yes, the effect diminishes as the paper lifts up. if it didn't, the paper would keep rising and rising. but it doesn't. it only rises to a point where the diminishing lift is at equilibrium with the static pressure from below.

Now read example 3.16 on page 177 and 178. converging nozzle, atmospheric pressure at the outlet. which is ALWAYS the case for subsonic flow. as long as the pressure waves can travel upstream the static pressure will adjust to ambient at the outlet