In the comics, Tony Stark's age can vary depending on the specific storyline and continuity. But generally, he's depicted as an adult in his 40s or 50s.
There are many fanfictions on this topic. In some, Tony Stark might be watching Peter Parker's growth as Spider - Man during the events of 'Homecoming' with a sense of pride, like a mentor observing his protege. He could be making mental notes about how Peter handles different situations.
Well, it all started when Tony was kidnapped and forced to build weapons. He then built a suit to escape and decided to use his tech for good, becoming Iron Man.
Yes, Tony Stark does know who Spider-Man is in the comics. They have interacted and formed significant relationships over the course of various storylines.