does the recipient pay for connection time (like a conventional voice call?)
Erm, you don't pay to receive calls in the UK, do you? We do in the US, but not there, shirly.
Sometimes G-Mail seems to show quite large pictures without invitation. Not sure when it chooses to do this, but mostly I would have to instruct it to download anything that was akin to a large .jpg The phone user could choose not to do this of course.
A regular Ppruner and I were walking along the Essex coastline, and I made mention of a ship/boat moored near the windfarm. He pulls out his iPhone I think it is, and soon shows me a plan of the sea and the boats and the names of the boats and the speed of the boats and where they are going.
One was impressed.
The only APP that I covet is one where you hold the phone over your head and look at that patch of stars. I haven't really put it's accuracy to the test however.