New wholesaler questions about rehab costs, escrow and procedures

[Alexander Johnson]

Hi everyone, I've been obsessed with re investing lately, read like 15 books, more than I've read in 15 years. I listen to the podcast and I watch videos, but there are a few questions I still have. 

1. It seems like people say get your buyer's list first, and I've got about 4 buyers lined up now. So my question is, when I find a deal, do I secure the exact sale price with the investor before I make an offer to the seller? Or is common practice to make an offer then find a buyer? That seems irresponsible, what if I mess up the numbers and can't find a buyer? I dont want to screw over vulnerable sellers but I also can't afford to buy a house. 

2. Why do I need an escrow company? Wouldn't the investor deal with that?

3. What's the safest way to determine rehab costs?

4. Is there a source for prewritten contracts or will I need to hire a lawyer?

Thank you all so much. I'm scheduled for all sorts of reia and other real estate meet ups but I'm really obsessed with learning this stuff now.