Flipping Advice - indianapolis

[Monique Pett]

Hi guys! 

So buy n holds are typically my forte, but I'm venturing into flipping. Have an off market home in indy, they wan $50k for it. Contractor says $40k worth of work is needed. Comps are supporting listing at $150k. 

Contractor wants 30 down, 30% 50% complete 30% 75% complete, and 10% on completion. 

What other questions should I ask? How do you triple check comps to verify? What else am I missing? 

Thanks, y'all! :)