Not really. A typical IOT client sends a few bytes every few minutes or hours. that's not much.

But the "internet of watching things", a world full of connected cameras is a different story. But it ain't a great slogan :)

To some extent. But most IoT applications aren't about heavy back-end processing. They are about capturing things that were to small to bother with before. The amazon dash buttons would actually save them a few page loads when you order tide because they never had to load the gui. If your fridge is emailing your shopping list to some server once a day ( assume it makes 5 or 6 calls while you cook dinner or whatever ) so again you're not making a huge impact on a server. It may be some increase, but much of that is probably offset as we become better at over subscription of huge servers.