Need help understand this example
Hello guys,
I don't understand this dictionary example:
高校時代の同級生と 駅前でばったり会い、近くの喫茶店で 数時間積もる話に花を咲かせた。
It's translated as follows:
I bumped into a classmate from high school in front of the station, and we spent a good few hours chatting happily at a nearby coffee shop.
First, what's the clue the speaker only met one student? Second, I need a breakdown of 数時間積もる話に花を咲かせた。and why it's translated like that.