You don't need to explain RSS any more than you need to explain SMTP or HTTP. A product that uses RSS could gain traction without the user ever knowing it uses RSS. Products like Google Reader prove that is possible.
Feedly does this. Just drop the URL of whatever source you want to follow and it figures out the feed for it behind the scenes. For popular sources, you don't even need the URL, just type in "Ars Technica" or whatever and it does the right thing.
Yes, but very few people use Feedly, which is why they had to shift to enterprise with trend watching and other tools. Platforms like Inoreader and Feedbin are pure RSS plays and their audience is a good benchmark of how much people actually want this.