1. He is going to study at
art school (per Tes above, thank you) and become a painter, something he has always wanted to be; or "He's planning to attend an art school hoping to become a painter, a job he's always wanted"
2. 2. He will be the best NBA player next year. Help, we need a sports fan
3. The train is leaving at 8 am Sunday. It is certain. Or "It's sure the train is leaving (at) 8 a.m. Sunday"
4. Liverpool will win the next championship league. Help...
5. That bicycle rider (or "cyclist," thanks to Mark above) is driving too fast. He's going to crash. or "That bike rider is goin' too fast and he's gonna crash"