Startup & Investors

I am planning for a startup, I am almost completed my ground work which i have been doing for 2 years. It is all about finding a cheapest deal on internet. We have done complete research on this area.

I have following queries. 1) How to write startup funding? 2) If i am planning to with investor how much and when i should repay the money. EX: If investor is investing 20,000$ when i should repay the profit 3) Once after investing if the investor is not profitable. Should i need to repay the money or investor invested on his own risk.